ISO/FDIS 5667-4
(Main)Water quality — Sampling — Part 4: Guidance on sampling from lakes, natural and man-made
Water quality — Sampling — Part 4: Guidance on sampling from lakes, natural and man-made
ISO 5667-4:2016 gives guidelines for the design of sampling programmes, techniques and the handling and preservation of samples of water, from natural and man-made lakes during open-water and ice-covered conditions. It is applicable to lakes with and without aquatic vegetation. Guidance on sampling for microbiological examination is not included.
Qualité de l'eau — Échantillonnage — Partie 4: Lignes directrices pour l'échantillonnage des eaux des lacs naturels et des lacs artificiels
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FINAL DRAFT
International
Standard
ISO/TC 147/SC 6
Water quality — Sampling —
Secretariat: BSI
Part 4:
Voting begins on:
Guidance on sampling from lakes,
natural and man-made
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Qualité de l'eau — Échantillonnage —
Partie 4: Lignes directrices pour l'échantillonnage des eaux des
lacs naturels et des lacs artificiels
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Reference number
FINAL DRAFT
International
Standard
ISO/TC 147/SC 6
Water quality — Sampling —
Secretariat: BSI
Part 4:
Voting begins on:
Guidance on sampling from lakes,
natural and man-made
Voting terminates on:
Qualité de l'eau — Échantillonnage —
Partie 4: Lignes directrices pour l'échantillonnage des eaux des
lacs naturels et des lacs artificiels
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2025
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling equipment . 3
4.1 Material selection . .3
4.2 Cleaning .3
4.3 Maintenance .3
5 Design of the sampling programme . 3
6 Sampling procedure . 4
6.1 General .4
6.2 Sampling location .4
6.2.1 General .4
6.2.2 Horizontal distribution of sampling positions .4
6.2.3 Vertical distribution of sampling points .5
6.3 Frequency and timing of sampling .5
6.4 Choice of sampling method.5
6.5 Choice of the sampling device .6
6.6 Aids for recovery of lost sampling equipment .6
6.7 Blank sample .6
6.8 Transport, stabilization and keeping of samples .6
7 Occupational health and safety . 6
8 Sample containers . 7
9 Priority of procedure . 7
10 Sample collection, contamination with environmental materials . 8
11 Rinsing the sampling equipment . 9
12 Sampling surface or near-surface water with an open sampling device . 9
12.1 General .9
12.2 Sampling .9
12.3 Filling multiple containers .9
13 Sampling with closed samplers . 10
14 Sampling for volatile parameters .10
15 Sampling through ice .10
16 Severe freezing conditions .11
17 Sample identification and records .11
18 Quality assurance and quality control .11
18.1 General .11
18.2 Avoidance of contamination . 12
Annex A (informative) Examples of sampling devices . 14
Annex B (informative) Advantages and disadvantages of sampling equipment.27
Annex C (informative) Sampling from boats — Maintaining station .28
Annex D (informative) Example of a report — Sampling from lakes, natural and man-made .30
Annex E (informative) Continuous measurement of water samples with immersion probes .31
Bibliography .33
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
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this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 6,
Sampling (general methods).
This third edition cancels and replaces the second edition (ISO 5667-4:2016), of which it constitutes a minor
revision.
The change is as follows: the following line has been added to the scope: “For specific guidance on the
sampling for microplastics, see ISO 5667-27”.
A list of all parts in the ISO 5667 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
FINAL DRAFT International Standard ISO/FDIS 5667-4:2025(en)
Water quality — Sampling —
Part 4:
Guidance on sampling from lakes, natural and man-made
1 Scope
This document gives guidelines for the design of sampling programmes, techniques and the handling and
preservation of samples of water, from natural and man-made lakes during open-water and ice-covered
conditions. This document is applicable to lakes with and without aquatic vegetation.
Guidance on sampling for microbiological examination is not included. For specific guidance on the sampling
for microplastics, see ISO 5667-27.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
grab sample
single discrete sample collected from a body of water at a specific time, location and depth
3.2
depth profile sample
two or more discrete samples collected at two or more depths at a specific time and location on a lake
3.3
area profile sample
two or more discrete samples collected from the same depth at two or more locations on a lake
3.4
composite sample
two or more depth profile (3.2) or area profile samples (3.3) that are combined to form a single sample prior
to measurement of water quality parameters
3.5
integrated sample
single sample collected by a tube or similar sampler that collects a water sample across a range of depths
3.6
in-situ measurement
measurement of a water quality parameter made within a body of water, not requiring collection of a
water sample
Note 1 to entry: The measurement is generally taken by use of an electronic probe.
3.7
ex-situ measurement
measurement of a water quality parameter made outside a body of water, and requiring collection and
possibly transport of a water sample prior to measurement
3.8
open sampling device
open-mouthed vessel, including beakers, buckets, containers or tubes, used for sampling at or near the water
surface (<1 m depth)
Note 1 to entry: Open sampling devices are not suitable for sampling for volatile parameters or dissolved gases.
3.9
closed sampling device
vertically or horizontally aligned hollow-bodied tube, pipe, box or container fitted with shutters, valves,
stoppers or other devices to prevent
— entry of air into the device,
— entrapment of air with the water sample, and
— the exchange of water between the collected sample and the surrounding water column
Note 1 to entry: Closed sampling devices are used for collecting water samples from deeper waters or for collection of
water samples for the analysis of volatile parameters and dissolved gases.
3.10
sampling pole
pole or rod with a terminal apparatus that accepts an open or closed sampling device (3.9) and that is used to
extend the reach of samplers
3.11
sampling iron
weighted container holder attached to a line and used to extend the reach of samplers or to submerse a
sample container to a specific depth
3.12
pumping device
hand or motor operated suction or submersible pumps, or pneumatic ejection samplers used for collection of
samples from defined depths or a series of depths
3.13
filling device
funnel, ladle, churn sample splitter or other device used to transfer sample water from a sampling device to
a sampling container
3.14
negative control
quality control sample that is used to ensure a negative response
4 Sampling equipment
4.1 Material selection
Sampling probes, devices and other equipment should be chosen, as far as possible, which do not give rise
to any interaction between the water and the material composition. The equipment and devices to be used
should be checked at random for the presence of emission, absorption and adsorption of substances or
influence of properties that are to be determined in the samples to be taken. Examples of common sampling
equipment are summarized in Annex A. Advantages and disadvantages of sampling equipment are provided
in Annex B. If a boat, marine vessel or any floatation device is used, care shall be taken so that it does not
result in contamination of the samples. Additional details regarding sampling from a vessel are summarized
in Annex C. A winch with steel rope and counter is advisable for deeper lakes. This ensures the required
sinking and resurfacing velocity of the sampling devices. Any solvents, chemicals or fuels should be stored
in sealed non-permeable containers. For example, the use of electric motors on small boats can be of value
in eliminating the risk of contamination by combustion exhaust and engine lubricants. ISO 5667-14 provides
guidance for checking the uptake and emission of the substances to be measured by equipment and devices
that are used for sampling.
4.2 Cleaning
A proper quality assurance and quality control (QA/QC) system should be in place to prevent contamination
and detect any contamination that can affect analytical results. All equipment and devices should be
regularly mechanically and, if appropriate, chemically cleaned, both internally and externally, to prevent
contamination of water samples.
4.3 Maintenance
Where equipment uses mechanical or other triggering devices, these mechanisms should be regularly
tested. Electronic devices and probes should be tested and calibrated according to the manufacturer’s
recommendations. A log of testing and calibration dates and results should be maintained.
5 Design of the sampling programme
Proper sampling is critical to ensure the quality of the investigation and resulting data. Developing a detailed
sampling strategy prior to collecting samples will minimize any sampling errors and will provide the most
representative sample for analysis. General aspects that should be considered in a sampling programme are
summarized in ISO 5667-1. These include, but are not limited to, the following:
a) purpose of the investigation;
b) parameters to be analysed for each sampling point;
c) measurements to be carried out at the sampling point as specified in the analytical method, e.g.
temperature, dissolved oxygen, pH, turbidity, conductivity;
d) frequency and times of sampling and type of sample;
e) sampling site and the number and locations of sampling points;
f) sampling equipment;
g) quality assurance procedures to be followed;
h) transport preservation and storage of samples;
i) hydrodynamic and morphologic characteristics of the water sampled;
j) local circumstances such as water depth, vegetation, accessibility of location and other potential
obstacles such as floating layers or sludge layers present;
k) sampling depth(s);
l) composition and quantity of the water to be sampled;
m) safety considerations.
6 Sampling procedure
6.1 General
As recommended in ISO 5667-1, an investigation plan should be established before a sampling program is
initiated. The plan should include:
— the purpose of the investigation;
— parameters to be analysed for each sampling site;
— frequency and times of sampling;
— the type of collection gear and containers;
— the number and locations of sampling points;
— sample preservation requirements;
— access and safety concerns;
— hydrodynamic, morphological and biological characteristics of the sampling site(s);
— the sampling depth(s); and
— the quantity of water to be collected.
Either phytoplankton or chlorophyll, or both, as well nutrients for water protection issues, should be sampled
in the euphotic zone or mixed layer, respectively. The decision down to which depth an integrated sample
[5]
has to be taken should be done according to EN 16698 . The decision depends on lake type, stratification
and phytoplankton turbidity. That means before the sampling procedure, the current probe measurement
data and Secchi disk readings have to be available.
6.2 Sampling location
6.2.1 General
General guidance is given in ISO 5667-1.
Samples from surface layers containing floating material should be taken with special surface samplers.
The spatial distribution of sampling locations can be properly decided only after detailed preliminary work
using a large number of sampling locations to provide information to which statistical techniques may be
applied.
6.2.2 Horizontal distribution of sampling positions
6.2.2.1 Sampling point for characterization of water quality
Morphologically complex lakes, those either consisting of several basins or having a complicated shoreline
can show significant heterogeneities in a horizontal direction. In order to evaluate the extent of such
heterogeneities, it is necessary to set up several sampling points to carry out preliminary investigations.
The data gathered then enable the necessary number of sampling points to be fixed effectively. One
sampling point above the deepest part of the lake is generally sufficient for lakes showing no significant
heterogeneities in a horizontal direction. Sampling points should be defined clearly, and if possible, marked
with buoys. Use navigation devices to identify the sampling points if the surface area is too large to allow the
fixing of buoys. If appropriate to the sampling purpose, samples can be collected from the lake shore, ideally
at or near the outflow, or jetty or promontory, using a device such as a sampling iron or sampling pole.
6.2.2.2 Sampling point for quality control
Negative control samples should be taken such that they are not influenced by potential sources of
contamination. These can include other nearby non-impacted areas or other nearby bodies of water that are
representative of the body of water being sampled.
6.2.2.3 Sampling point for special investigations
Samples should be taken as single or replicate samples where unusual phenomena have been observed. The
sites should be clearly identified in the report, with a map or sketch where possible.
6.2.3 Vertical distribution of sampling points
The water quality in natural and man-made lakes can show large vertical heterogeneities due to
stratification. The reasons for these are influences from the water surface (changes of the water quality by
photosynthesis in the euphotic zone and changes in water temperature by heating) and influences arising
from the sediment (dissolution or resuspension of substances from the sediment). Furthermore, vertical
heterogeneities can arise from sedimentation of suspended matter. Large differences in water quality
are also frequently observed at the thermocline. For these reasons, the distance between grab sample
depths in heterogeneous zones should be minimized. The exact arrangement of sampling levels depends
on the information required and the local circumstances. It is therefore advisable to carry out preliminary
investigations using measuring probes (for measurement of temperature, if possible, as well as dissolved
oxygen concentration, pH value, conductivity, turbidity and chlorophyll fluorescence), which allow either
continuous monitoring or monitoring at short intervals. In such cases, stagger the sampling depth to allow
the recording of all vertical heterogeneity. Once a sampling programme has been defined, it should be
carried out to completion, since if it is altered during sampling, the data gathered will be incompatible. In
large and deep bodies of water where internal movement of water can occur, the use of a series of samplers,
which all take samples simultaneously, is recommended.
6.3 Frequency and timing of sampling
Detailed guidance, including statistical considerations, is given in ISO 5667-1.
The water quality of natural and man-made lakes varies seasonally. Consequently, the frequency of sampling
will depend on the information required.
In general, for lentic waters, an interval of one month or longer between the collection of consecutive samples
is acceptable for water quality characterization over a long period of time. For the purpose of quality control
measurement, a minimum interval of one week is necessary. If rapid changes in water quality are apparent,
daily or even continuous sampling can be necessary.
Lake sampling four times a year will allow an acceptable water quality characterization over a long period of
time. For the purpose of quality control measurement, a higher frequency can be required.
In addition, quality can vary significantly during a day. Samples should be taken at about the same time of
the day. If daily variation is of special interest, sampling every 2 h or 3 h is recommended.
6.4 Choice of sampling method
The choice of sampling method depends on the objective of the sampling programme. Samples taken for
special reasons or for quality control purposes will, in most cases, be grab samples. For monitoring water
quality, a series of grab samples is used, but composite samples can be useful. The analysis of a series of grab
samples can be costly and these are often combined to reduce analytical costs; however, composite samples
will indicate only mean values and will not reveal details of extreme conditions or the extent of quality
variation. Both methods may be combined by taking composite samples at short intervals and a series of
samples at longer intervals.
6.5 Choice of the sampling device
The choice of the sampling device depends on the objective of the sampling program. Samples taken for
special reasons or for quality control purposes will be, in most cases, grab samples (see Annex A for examples
of sampling devices). For monitoring water quality, a series of grab samples is often used, but composite
samples may be useful, especially for the investigation of defined water layers, e.g. the epilimnion or the
euphotic zone. However, composite samples will indicate only mean values and will not reveal details of
extreme conditions or the extent of quality variation.
Immersion probes may be used for a continuous measurement of pH or dissolved oxygen in unstable water
samples (see Annex E).
6.6 Aids for recovery of lost sampling equipment
When handing sampling devices in small boats, there is an increased risk of losing equipment overboard. It
is recommended that the trailing end of the tether line comprises of “floating rope” to aid recovery should
the equipment be lost in shallow waters. Floating ropes are designed as safety products that remain near
the surface for easy capture and recovery of objects to which they are attached. They are readily available
for a range of safety applications and load ratings.
6.7 Blank sample
When collecting and processing water samples, it is necessary to include blank samples such as field blanks,
travel blanks and filter blanks to measure the degree of contamination that may have been introduced
into the samples as a result of sampling related activities. Detailed guidance on the use of blanks and other
quality control samples is given in ISO 5667-14.
6.8 Transport, stabilization and keeping of samples
ISO 5667-3 gives general guidance on sample handling and preservation.
Ensure that sample containers are delivered to the laboratory tightly sealed and protected from the effects
of light and excessive heat, because the quality can change rapidly due to gas exchange, chemical reactions
and the metabolism of organisms. Ensure that samples which cannot be analysed quickly are filtered (if
required by specific analytical method) and stabilized or preserved if required. The method of preservation
shall be chosen to avoid interference with the parameters of interest and does not interfere with the
subsequent examination or influence the results. Where particles or biological activity in the sample are
expected to influence parameters of interest, the sample may be filtered on site to remove particles or
organisms and the filter held separately for analysis. For storage over short periods, cooling to 5 °C ± 3 °C
may be applied; for keeping over longer periods, freezing to −18 °C is advisable. In the latter case, ensure
the sample is completely thawed before use as the freezing process can have the effect concentrating some
components of the inner part of the sample which freezes last. Samples may be preserved by the addition of
chemicals. Record all preservation steps in the report. Measure and record the temperature on site. Ideally,
other physical parameters (pH, for example) should be determined on site. If free carbon dioxide is present,
measure the pH in situ.
7 Occupational health and safety
ISO 5667-1 specifies safety precautions including, but not limited to, sampling from boats and ice-covered waters.
NOTE The user's attention is drawn to the existence of national or local health and safety regulations.
8 Sample containers
Sample containers should be selected on the basis of the parameters to be analysed and be made of materials
that do not lead to contamination of samples. ISO 5667-3 provides further guidance on the selection of
sample containers. Depending on parameters to be analysed, sample containers can require laboratory pre-
treatment, including acid-washing, cleaning or quality control procedures or on-site rinsing to be performed
prior to use. Guidance should be sought from the analytical laboratory with respect to the selection and
use of sampling containers and the volume of sample required to be collected. This guidance should be
documented in formal, written protocols. Where containers are pre-treated, precautions should be taken to
avoid exposure to chemicals used in the pre-treatment process.
9 Priority of procedure
Prior to taking samples, it is important to take the Universal Transverse Mercator (UTM) coordinates and
water depth to ensure samples were collected in the correct location. This is typically the deepest point of
the lake.
In order to reduce the risk of contamination of water samples, choose methods that reduce the number
of water transfers between sample collection devices, filling devices and sample containers. In order of
preference (see Table 1),
— conduct in-situ measurement of parameters of interest,
— collect water samples using direct filling of sampling containers for ex-situ analysis without the use of
sampling devices, funnels or other equipment,
— conduct indirect filling of sampling containers for ex-situ analysis where sampling devices are used to
collect water samples that are later distributed directly into one or more sample containers, and
— conduct indirect collection of samples for ex-situ measurement, whereby sampling devices collect water
samples that are later distributed into one or more sample containers.
In situ water quality measurements including dissolved oxygen, pH, water temperature, conductivity,
turbidity and light penetration, by Secchi disk depth or light probe, can guide depth stratified sampling
of thermally or chemically stratified waters by permitting pre-sampling assessment of the chemical and
physical structure of the water column and therefore should be completed before the collection of physical
water samples occurs. Depth measurements should be consistently repeated in stratified waters to ensure
depth sensitive parameters such as pH and dissolved oxygen are sampled correctly.
Secchi disks can take a number of different forms including 30 cm diameter white and 20 cm diameter
with every quarter of the disk alternating between black and white. Details of the disks and procedure are
summarized in ISO 7027. A brief description is listed as follows.
a) Lower the Secchi disk to the point of disappearance.
b) Raise the disk until it reappears and then lower it until it disappears a second time.
c) Note the depth.
d) Repeat the procedure until a constant result is obtained.
Measurements should be taken such that environmental conditions, e.g. wind and glare from the sun, are
minimized. Care shall be taken as to not disturb the sampling area (the use of an underwater viewscope
can be desirable). If a motorized vessel with propeller is used, the engine should be shut off at least 10 m
from the sampling area. Position and anchor the motorized vessel so that vessel does not contaminate the
sampling area.
Table 1 — Priorities in measurement of a water quality parameter including dissolved oxygen, pH,
water temperature and turbidity
Measurement of a water quality parameter including dissolved oxygen, pH,
water temperature, turbidity
Priority of procedure Comments Records
Location of the
sampling point
Equipment used for
measurement and for
sampling
— Values of temperature Method of
and oxygen unbiased (no measurement
exchange with air and no Values of measurement
heating of the sample)
— Risk: Value of Method of
temperature biased (heat- measurement
ing of the sample) Values of measurement
— Value of oxygen
unbiased (no exchange
with air)
— Risks: Values of Method of
temperature and oxygen measurement
biased (exchange with air Values of measurement
and heating of the sample)
10 Sample collection, contamination with environmental materials
To avoid contamination of water samples during collection, the following guidelines are provided.
— Samples should be collected from the upwind or upstream side of an anchored boat.
— Samples should be collected from the downwind side of a drifting boat.
— Where depth profile samples are collected, sampling should commence at the surface of the water column
and proceed downwards through the water column.
— When samples are collected during the course of wading, samples should be collected forward of the
waders path or upwind of the sampler.
— Samples should be collected in a manner that does not permit contamination by motor exhausts, dust,
debris and bottom sediments.
— Samples should be collected as to avoid collection devices or containers scraping against docks, poles,
preserved lumber and other infrastructure, boat hulls and antifouling coatings.
— Unless specified in the investigation plan, the sample should not include the surface film of the water or
floating layers.
— When sampling through ice, ice chips, ice-water slurry, meltwater and snow should not be allowed to
enter the sample container.
— When sampling waters covered in vegetation, care should be taken not to disturb the vegetation or allow
any of the vegetation to enter the sample container.
11 Rinsing the sampling equipment
All the equipment that comes in contact with the water should be rinsed, using water from the body of water
to be sampled. Rinse all the equipment used for sampling preferably up to three times.
If the analytical method requires the sample containers to be rinsed, remove the caps prior to taking the
rinse water, handling the caps in such a way that the interior surface does not become contaminated,
preferably holding them in one hand or keeping them in a polyethylene bag. Follow the instructions in
ISO 5667-3 for rinsing sampling containers. It is important that sample containers are not rinsed if they
contain preservatives.
If using a rope or chain, pour some of the contents of the sample vessel rinse contents over the final metre
of the rope or chain to wash off all traces of previous samples. Remove as much excess liquid as possible by
shaking. Do not allow this part of the rope or chain to be re-contaminated by allowing it to come in contact
with the ground or any other surface. Similarly, rinse the end of the sampling pole if used.
12 Sampling surface or near-surface water with an open sampling device
12.1 General
Extra precautions should be taken for the analysis for volatile parameters including dissolved gases and
volatile organic compounds (see Clause 14).
12.2 Sampling
If applicable, attach the sample container to a sampling pole or iron. Displace the floating layer by first
making a rotating movement with the container on the water surface. Rinse the sample container, preferably
up to three times, with surface water as required by the sampling protocol or as directed by the laboratory.
Submerge the sample container to the sampling depth, turn it around and allow the container to fill.
Ensure that bubbles are not collected during the sampling procedure. Hold the sample container at about a
45° angle to allow bubbles to escape the sample container.
If conducting direct sampling, seal the sample container and proceed to post-sampling requirements for the
samples.
If indirect water sampling is to be employed, rinse the filling devices and sample container as required by
the investigation plan. Fill the filling device and dispense the water sample into the sample container(s). Seal
the sample container.
12.3 Filling multiple containers
If filling more than a single sample container from a single sample collection is required, ensure that the
sample remains homogeneously mixed during filling of the sample container, by using, for example, a churn
sample splitter to dispense sample water among the sample containers.
Where several collections of water samples from a single sampling site are required to fill multiple sample
containers, either
a) combine the sample collections in a larger container, such as a churn sample splitter, before allocation to
sample containers, or
b) use sample water from individual collections to completely fill sample containers for independent sets
of inter-related parameters.
Fill all sample containers needed for phosphorus fractions from the same collection, sample containers for
anions and cations may be filled from a second collection, sample containers for dissolved and suspended
heavy metals from a third collection.
Where depth or area composite samples are to be dispensed into multiple sample containers, mix the
constituent samples of the composite sample in a churn sample splitter or similar device prior to dispensing
sample water.
Samples should be collected and preserved according to specific requirements with respect to the method
for which the samples have been taken.
13 Sampling with closed samplers
Closed samplers are typically used to sample volatile and non-volatile parameters in deeper waters,
generally greater than 1 m depth, and for volatile compounds in shallow waters. In general, horizontal closed
samplers are used in shallow or flowing waters while vertical samplers are used for deep, standing waters.
Lower the open sampling device slowly into the water column to the required depth, avoiding dynamic
pressure, allowing it to rinse as it descends. Seal the device when it has reached the desired depth and filled
with sample water. Remove it from the water. Rinse any filling devices and containers with sample water
as required. Fill containers as required. When multiple sample containers are to be filled or where multiple
collections are to be made, the procedures described in 12.3 should be followed. Samplers with lids that
do not uncover the entire cross-section area of the sampling tube while lowered in the water (e.g. Ruttner-
sampler) are not appropriate.
14 Sampling for volatile parameters
Sampling volatile parameters requires the use of closed sampling or pumping devices. Following collection
of the water sample with a closed sampling device, fill the sample containers directly from the device.
Extend the outlet of the device with a polytetrafluoroethylene (PTFE) tube long enough to reach the bottom
of the sample container. Position the PTFE outlet on the bottom of the sample container and fill it with the
device. Fill the container until it overflows. Then, remove the outlet from the container while the water is
still flowing. Seal the sample container immediately after removal of the outlet. The sample container should
be completely filled, without any air bubbles.
When using a pumping device to collect the water sample, pump sample water directly into the sample
container using an appropriate outlet tube as described above. Suction pumps should not be used for
sampling volatile compounds as volatile organics and dissolved gases can be removed from the sample.
Where double sampling containers (see Figure 1) are used to sample volatile parameters in near-surface
waters, place the sampling containers at the required depth and wait until both containers have been
completely filled. Remove the PTFE stopper with inlet tube from the sampling container and seal this with a
ground-glass stopper. The sampling container should be completely filled, without any air bubbles.
15 Sampling through ice
Sampling through ice requires use of an ice chisel, auger or drill. Use a battery or hand-powered ice auger to
drill through the ice or an ice chisel when collecting samples for organics analyses, to reduce the possibility
of contamination of samples with gasoline, oil and combustion products. After drilling the hole, remove
all ice chips and snow from the hole and surrounding area prior to collection of the sample. Proceed with
collection as above but, if applicable, with recognition of the specific challenges of working under severe
freezing conditions. Strong gradients of pa
...
TC /SC
Date:
TC /SC /WG ISO/FDIS 5667-4
ISO/TC 147/SC 6
Secretariat: BSI
Date: 2025-10-16
Water quality — Sampling —
Part 4:
Guidance on sampling from lakes, natural and man-made
Qualité de l'eau — Échantillonnage —
Partie 4: Lignes directrices pour l'échantillonnage des eaux des lacs naturels et des lacs artificiels
FDIS stage
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: + 41 22 749 01 11
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Published in Switzerland
ii
Contents Page
Foreword . v
1 Scope . 6
2 Normative references . 1
3 Terms and definitions . 1
4 Sampling equipment . 3
4.1 Material selection . 3
4.2 Cleaning . 3
4.3 Maintenance . 3
5 Design of the sampling programme . 3
6 Sampling procedure . 4
6.1 General. 4
6.2 Sampling location . 5
6.3 Frequency and timing of sampling . 6
6.4 Choice of sampling method . 6
6.5 Choice of the sampling device . 6
6.6 Aids for recovery of lost sampling equipment . 6
6.7 Blank sample . 6
6.8 Transport, stabilization and keeping of samples . 7
7 Occupational health and safety . 7
8 Sample containers . 7
9 Priority of procedure . 7
10 Sample collection, contamination with environmental materials. 9
11 Rinsing the sampling equipment . 9
12 Sampling surface or near-surface water with an open sampling device . 9
12.1 General. 9
12.2 Sampling . 9
12.3 Filling multiple containers . 10
13 Sampling with closed samplers . 10
14 Sampling for volatile parameters . 11
15 Sampling through ice . 11
16 Severe freezing conditions . 11
17 Sample identification and records . 12
18 Quality assurance and quality control . 12
18.1 General. 12
18.2 Avoidance of contamination . 12
Annex A (informative) Examples of sampling devices . 14
Annex B (informative) Advantages and disadvantages of sampling equipment . 28
Annex C (informative) Sampling from boats — Maintaining station . 29
Annex D (informative) Example of a report — Sampling from lakes, natural and man-made . 31
Annex E (informative) Continuous measurement of water samples with immersion probes . 33
Bibliography . 35
iii
iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO documentsdocument should be noted. This document was drafted in accordance with the editorial rules
of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawnISO draws attention to the possibility that some of the elementsimplementation of this
document may beinvolve the subjectuse of (a) patent(s). ISO takes no position concerning the evidence,
validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this
document, ISO had not received notice of (a) patent(s) which may be required to implement this document.
However, implementers are cautioned that this may not represent the latest information, which may be
obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for
identifying any or all such patent rights. Details of any patent rights identified during the development of the
document will be in the Introduction and/or on the ISO list of patent declarations received (see ).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation onof the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT)), see
www.iso.org/iso/foreword.htmlthe following URL: .
The committee responsible for thisThis document iswas prepared by Technical Committee ISO/TC 147, Water
quality, Subcommittee SC 6, Sampling (general methods).
This secondthird edition cancels and replaces the firstsecond edition (ISO 5667--4:1987),2016), of which has
been technically revised.it constitutes a minor revision.
ISO 5667 consists of The change is as follows: the following parts, underline has been added to the general
title Water quality — Sampling:
— Part 1: Guidancescope: “For specific guidance on the design of sampling programmes and
sampling techniquesfor microplastics, see ISO 5667-27”.
A list of all parts in the ISO 5667 series can be found on the ISO website.
— Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html— Part 3:
Preservation and handling of water samples
— .
v
Water quality — Sampling —
Part 4:
Guidance on sampling from lakes, natural and man-made
— — Part 5: Guidance on sampling of drinking water from treatment works and piped distribution
systems
— — Part 6: Guidance on sampling of rivers and streams
— — Part 7: Guidance on sampling of water and steam in boiler plants
— — Part 8: Guidance on the sampling of wet deposition
— — Part 9: Guidance on sampling from marine waters
— — Part 10: Guidance on sampling of waste waters
— — Part 11: Guidance on sampling of groundwaters
— — Part 12: Guidance on sampling of bottom sediments
— — Part 13: Guidance on sampling of sludges
— — Part 14: Guidance on quality assurance and quality control of environmental water sampling and
handling
— — Part 15: Guidance on the preservation and handling of sludge and sediment samples
— — Part 16: Guidance on biotesting of samples
— — Part 17: Guidance on sampling of bulk suspended solids
— — Part 19: Guidance on sampling of marine sediments
— — Part 20: Guidance on the use of sampling data for decision making — Compliance with thresholds
and classification systems
— — Part 21: Guidance on sampling of drinking water distributed by tankers or means other than
distribution pipes
— — Part 22: Guidance on the design and installation of groundwater monitoring points
— — Part 23: Guidance on passive sampling in surface waters
— — Part 24: Guidelines for the auditing of water quality sampling
vi
1 Scope
This part of ISO 5667document gives guidelines for the design of sampling programmes, techniques and the
handling and preservation of samples of water, from natural and man-made lakes during open-water and ice-
covered conditions. This part of ISO 5667document is applicable to lakes with and without aquatic vegetation.
Guidance on sampling for microbiological examination is not included. For specific guidance on the sampling
for microplastics, see ISO 5667-27.
2 Normative references
The following documents, are referred to in wholethe text in such a way that some or in part, are normatively
referenced inall of their content constitutes requirements of this document and are indispensable for its
application. For dated references, only the edition cited applies. For undated references, the latest edition of
the referenced document (including any amendments) applies.
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and sampling
techniques
ISO 5667--3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 5667-14, Water quality — Sampling — Part 14: Guidance on quality assurance and quality control of
environmental water sampling and handling
ISO 7027, Water quality — Determination of turbidity
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp3.1
— IEC Electropedia: available at https://www.electropedia.org/
3.1
grab sample
single discrete sample collected from a body of water at a specific time, location and depth
3.2 3.2
depth profile samplessample
two or more discrete samples collected at two or more depths at a specific time and location on a lake
3.3 3.3
area profile samplessample
two or more discrete samples collected from the same depth at two or more locations on a lake
3.4 3.4
composite sample
two or more depth profile (Error! Reference source not found.(3.2)) or area profile samples (Error!
Reference source not found.(3.3)) that are combined to form a single sample prior to measurement of water
quality parameters
3.5 3.5
integrated sample
single sample collected by a tube or similar sampler that collects a water sample across a range of depths
3.6 3.6
in-situ measurement
measurement of a water quality parameter made within a body of water, not requiring collection of a water
sample
Note 1 to entry: The measurement is generally taken by use of an electronic probe.
3.7 3.7
ex-situ measurement
measurement of a water quality parameter made outside a body of water, and requiring collection and
possibly transport of a water sample prior to measurement
3.8 3.8
open sampling device
open-mouthed vessel, including beakers, buckets, containers or tubes, used for sampling at or near the water
surface (<1 m depth)
Note 1 to entry: Open sampling devices are not suitable for sampling for volatile parameters or dissolved gases.
3.9 3.9
closed sampling device
vertically or horizontally aligned hollow-bodied tube, pipe, box or container fitted with shutters, valves,
stoppers or other devices that prevent entry of air into and/or enclosure of air with the water sample and the
exchange of water between the collected sample and the surrounding water columnto prevent
— entry of air into the device,
— entrapment of air with the water sample, and
— the exchange of water between the collected sample and the surrounding water column
Note 1 to entry: Closed sampling devices are used for collecting water samples from deeper waters or for collection of
water samples for the analysis of volatile parameters and dissolved gases.
3.10 3.10
sampling pole
pole or rod with a terminal apparatus that accepts an open or closed sampling device (Error! Reference
source not found.(3.9)) and that is used to extend the reach of samplers
3.11 3.11
sampling iron
weighted container holder attached to a line and used to extend the reach of samplers or to submerse a sample
container to a specific depth
3.12 3.12
pumping device
hand or motor operated suction or submersible pumps, or pneumatic ejection samplers used for collection of
samples from defined depths or a series of depths
3.13 3.13
filling device
funnel, ladle, churn sample splitter or other device used to transfer sample water from a sampling device to a
sampling container
3.14 3.14
negative control
quality control sample that is used to ensure a negative response
4 Sampling equipment
4.1 Material selection
Sampling probes, devices and other equipment should be chosen, as far as possible, which do not give rise to
any interaction between the water and the material composition. The equipment and devices to be used
should be checked at random for the presence of emission, absorption and adsorption of substances or
influence of properties that are to be determined in the samples to be taken. Examples of common sampling
equipment are summarized in Annex AAnnex A. Advantages and disadvantages of sampling equipment are
provided in Annex BAnnex B. If a boat, marine vessel or any floatation device is used, care shall be taken so
that it does not result in contamination of the samples. Additional details regarding sampling from a vessel
are summarized in Annex CAnnex C. A winch with steel rope and counter is advisable for deeper lakes. This
ensures the required sinking and resurfacing velocity of the sampling devices. Any solvents, chemicals or fuels
should be stored in sealed non-permeable containers. For example, the use of electric motors on small boats
can be of value in eliminating the risk of contamination by combustion exhaust and engine lubricants.
ISO 5667--14 provides guidance for checking the uptake and emission of the substances to be measured by
equipment and devices that are used for sampling.
4.2 Cleaning
A proper quality assurance and quality control (QA/QC) system should be in place to prevent contamination
and detect any contamination that couldcan affect analytical results. All equipment and devices should be
regularly mechanically and, if appropriate, chemically cleaned, both internally and externally, to prevent
contamination of water samples.
4.3 Maintenance
Where equipment uses mechanical or other triggering devices, these mechanisms should be regularly tested.
Electronic devices and probes should be tested and calibrated according to the manufacturer’s
recommendations. A log of testing and calibration dates and results should be maintained.
5 Design of the sampling programme
Proper sampling is critical to ensure the quality of the investigation and resulting data. Developing a detailed
sampling strategy prior to collecting samples will minimize any sampling errors and will provide the most
representative sample for analysis. General aspects that should be considered in a sampling programme are
summarized in ISO 5667--1. These include, but are not limited to, the following:
a) a) purpose of the investigation;
b) b) parameters to be analysed for each sampling point;
c) c) measurements to be carried out at the sampling point as specified in the analytical method, e.g.
temperature, dissolved oxygen, pH, turbidity, conductivity;
d) d) frequency and times of sampling and type of sample;
e) e) sampling site and the number and locations of sampling points;
f) f) sampling equipment;
g) g) quality assurance procedures to be followed;
h) h) transport preservation and storage of samples;
i) i) hydrodynamic and morphologic characteristics of the water sampled;
j) j) local circumstances such as water depth, vegetation, accessibility of location and other
potential obstacles such as floating layers or sludge layers present;
k) k) sampling depth(s);
l) l) composition and quantity of the water to be sampled;
m) m) safety considerations.
6 Sampling procedure
6.1 General
As recommended in ISO 5667--1, an investigation plan should be established before a sampling program is
initiated. The plan should include: the purpose of the investigation; parameters to be analysed for each
sampling site; frequency and times of sampling; the type of collection gear and containers; the number and
locations of sampling points; sample preservation requirements; access and safety concerns; hydrodynamic,
morphological and biological characteristics of the sampling site(s); the sampling depth(s); and quantity of
water to be collected.
— Phytoplanktonthe purpose of the investigation;
— parameters to be analysed for each sampling site;
— frequency and/ times of sampling;
— the type of collection gear and containers;
— the number and locations of sampling points;
— sample preservation requirements;
— access and safety concerns;
— hydrodynamic, morphological and biological characteristics of the sampling site(s);
— the sampling depth(s); and
— the quantity of water to be collected.
Either phytoplankton or chlorophyll, or both, as well nutrients for water protection issues, should be sampled
in the euphotic zone or mixed layer, respectively. The decision down to which depth an integrated sample has
[ ]
to be taken should be done according to EN 16698 Error! Reference source not found. . The decision
depends on lake type, stratification and phytoplankton turbidity. That means before the sampling procedure,
the current probe measurement data and Secchi disk readings have to be available.
6.2 Sampling location
6.2.1 General
General guidance is given in ISO 5667--1.
Samples from surface layers containing floating material should be taken with special surface samplers.
The spatial distribution of sampling locations can be properly decided only after detailed preliminary work
using a large number of sampling locations to provide information to which statistical techniques may be
applied.
6.2.2 Horizontal distribution of sampling positions
6.2.2.1 Sampling point for characterization of water quality
Morphologically complex lakes, those either consisting of several basins or having a complicated shoreline can
show significant heterogeneities in a horizontal direction. In order to evaluate the extent of such
heterogeneities, it is necessary to set up several sampling points to carry out preliminary investigations. The
data gathered then enable the necessary number of sampling points to be fixed effectively. One sampling point
above the deepest part of the lake is generally sufficient for lakes showing no significant heterogeneities in a
horizontal direction. Sampling points should be defined clearly, and if possible, marked with buoys. Use
navigation devices to identify the sampling points if the surface area is too large to allow the fixing of buoys. If
appropriate to the sampling purpose, samples can be collected from the lake shore, ideally at or near the
outflow, or jetty or promontory, using a device such as a sampling iron or sampling pole.
6.2.2.2 Sampling point for quality control
Negative control samples should be taken such that they are not influenced by potential sources of
contamination. These couldcan include other nearby non-impacted areas or other nearby bodies of water that
are representative of the body of water being sampled.
6.2.2.3 Sampling point for special investigations
Samples should be taken as single or replicate samples where unusual phenomena have been observed. The
sites should be clearly identified in the report, with a map or sketch where possible.
6.2.3 Vertical distribution of sampling points
The water quality in natural and man-made lakes can show large vertical heterogeneities due to stratification.
The reasons for these are influences from the water surface (changes of the water quality by photosynthesis
in the euphotic zone and changes in water temperature by heating) and influences arising from the sediment
(dissolution or resuspension of substances from the sediment). Furthermore, vertical heterogeneities can
arise from sedimentation of suspended matter. Large differences in water quality are also frequently observed
at the thermocline. For these reasons, the distance between grab sample depths in heterogeneous zones
should be minimized. The exact arrangement of sampling levels depends on the information required and the
local circumstances. It is therefore advisable to carry out preliminary investigations using measuring probes
(for measurement of temperature, if possible, as well as dissolved oxygen concentration, pH value,
conductivity, turbidity and chlorophyll fluorescence), which allow either continuous monitoring or
monitoring at short intervals. In such cases, stagger the sampling depth to allow the recording of all vertical
heterogeneity. Once a sampling programme has been defined, it should be carried out to completion, since if
it is altered during sampling, the data gathered will be incompatible. In large and deep bodies of water where
internal movement of water can occur, the use of a series of samplers, which all take samples simultaneously,
is recommended.
6.3 Frequency and timing of sampling
Detailed guidance, including statistical considerations, is given in ISO 5667--1.
The water quality of natural and man-made lakes varies seasonally. Consequently, the frequency of sampling
will depend on the information required.
In general, for lentic waters, an interval of 1one month or longer between the collection of consecutive samples
is acceptable for water quality characterization over a long period of time. For the purpose of quality control
measurement, a minimum interval of one week is necessary. If rapid changes in water quality are apparent,
daily or even continuous sampling can be necessary.
Lake sampling four times a year will allow an acceptable water quality characterization over a long period of
time. For the purpose of quality control measurement, a higher frequency maycan be required.
In addition, quality can vary significantly during a day. Samples should be taken at about the same time of the
day. If daily variation is of special interest, sampling every 2 h or 3 h is recommended.
6.4 Choice of sampling method
The choice of sampling method depends on the objective of the sampling programme. Samples taken for
special reasons or for quality control purposes will, in most cases, be grab samples. For monitoring water
quality, a series of grab samples is used, but composite samples can be useful. The analysis of a series of grab
samples can be costly and these are often combined to reduce analytical costs; however, composite samples
will indicate only mean values and will not reveal details of extreme conditions or the extent of quality
variation. Both methods may be combined by taking composite samples at short intervals and a series of
samples at longer intervals.
6.5 Choice of the sampling device
The choice of the sampling device depends on the objective of the sampling program. Samples taken for special
reasons or for quality control purposes will be, in most cases, be grab samples (see Annex AAnnex A for
examples of sampling devices). For monitoring water quality, a series of grab samples is often used, but
composite samples may be useful, especially for the investigation of defined water layers, e.g. the epilimnion
or the euphotic zone. However, composite samples will indicate only mean values and will not reveal details
of extreme conditions or the extent of quality variation.
Immersion probes may be used for a continuous measurement of pH or dissolved oxygen in unstable water
samples (see Annex EAnnex E).).
6.6 Aids for recovery of lost sampling equipment
When handing sampling devices in small boats, there is an increased risk of losing equipment overboard. It is
recommended that the trailing end of the tether line comprises of “floating rope” to aid recovery should the
equipment be lost in shallow waters. Floating ropes are designed as safety products that remain near the
surface for easy capture and recovery of objects to which they are attached. They are readily available for a
range of safety applications and load ratings.
6.7 Blank sample
When collecting and processing water samples, it is necessary to include blank samples such as field blanks,
travel blanks and filter blanks to measure the degree of contamination that may have been introduced into
the samples as a result of sampling related activities. Detailed guidance on the use of blanks and other quality
control samples is given in ISO 5667--14.
6.8 Transport, stabilization and keeping of samples
ISO 5667--3 gives general guidance on sample handling and preservation.
Ensure that sample containers are delivered to the laboratory tightly sealed and protected from the effects of
light and excessive heat, because the quality maycan change rapidly due to gas exchange, chemical reactions
and the metabolism of organisms. Ensure that samples which cannot be analysed quickly are filtered (if
required by specific analytical method) and stabilized or preserved if required. The method of preservation
shall be chosen to avoid interference with the parameters of interest and does not interfere with the
subsequent examination or influence the results. Where particles or biological activity in the sample may
beare expected to influence parameters of interest, the sample may be filtered on site to remove particles or
organisms and the filter held separately for analysis. For storage over short periods, cooling to 5 °C ± 3 °C may
be applied; for keeping over longer periods, freezing to −18 °C is advisable. In the latter case, ensure the
sample is completely thawed before use as the freezing process can have the effect concentrating some
components of the inner part of the sample which freezes last. Samples may be preserved by the addition of
chemicals. Record all preservation steps in the report. Measure and record the temperature on site. Ideally,
other physical parameters (pH, for example) should be determined on site. If free carbon dioxide is present,
measure the pH in situ.
7 Occupational health and safety
ISO 5667--1 specifies safety precautions including, but not limited to, sampling from boats and ice-covered
waters.
NOTE The user's attention is drawn to the existence of national and/or local health and safety regulations.
8 Sample containers
Sample containers should be selected on the basis of the parameters to be analysed and be made of materials
that do not lead to contamination of samples. ISO 5667--3 provides further guidance on the selection of sample
containers. Depending on parameters to be analysed, sample containers can require laboratory pre-treatment,
including acid-washing, cleaning or quality assurance/quality control procedures or on-site rinsing to be
performed prior to use. Guidance should be sought from the analytical laboratory with respect to the selection
and use of sampling containers and the volume of sample required to be collected. This guidance should be
documented in formal, written protocols. Where containers are pre-treated, precautions should be taken to
avoid exposure to chemicals used in the pre-treatment process.
9 Priority of procedure
Prior to taking samples, it is important to take the UTM-Universal Transverse Mercator (UTM) coordinates
and water depth to ensure samples were collected in the correct location. This is typically the deepest point
of the lake.
In order to reduce the risk of contamination of water samples, choose methods that reduce the number of
water transfers between sample collection devices, filling devices and sample containers. In order of
preference (see 0Table 1),),
— — conduct in-situ measurement of parameters of interest,
— — collect water samples using direct filling of sampling containers for ex-situ analysis without the use of
sampling devices, funnels or other equipment,
— — conduct indirect filling of sampling containers for ex-situ analysis where sampling devices are used to
collect water samples that are later distributed directly into one or more sample containers, and
— — conduct indirect collection of samples for ex-situ measurement, whereby sampling devices collect
water samples that are later distributed into one or more sample containers.
In situ water quality measurements including dissolved oxygen, pH, water temperature, conductivity,
turbidity and light penetration, by Secchi disk depth or light probe, can guide depth stratified sampling of
thermally or chemically stratified waters by permitting pre-sampling assessment of the chemical and physical
structure of the water column and therefore should be completed before the collection of physical water
samples occurs. Depth measurements should be consistently repeated in stratified waters to ensure depth
sensitive parameters such as pH and dissolved oxygen are sampled correctly.
Secchi disks can take a number of different forms including 30 cm diameter white and 20 cm diameter with
every quarter of the disk alternating between black and white. Details of the disks and procedure are
summarized in ISO 7027. A brief description is listed as follows.
a) a) Lower the Secchi disk to the point of disappearance.
b) b) Raise the disk until it reappears and then lower it until it disappears a second time.
c) c) Note the depth.
d) d) Repeat the procedure until a constant result is obtained.
Measurements should be taken such that environmental conditions, e.g. wind and glare from the sun, are
minimized. Care shall be taken as to not disturb the sampling area (the use of an underwater viewscope can
be desirable). If a motorized vessel with propeller is used, the engine should be shut off at least 10 m from the
sampling area. Position and anchor the motorized vessel so that vessel does not contaminate the sampling
area.
Table 1 — Priorities in measurement of a water quality parameter including dissolved oxygen, pH,
water temperature and turbidity
Measurement of a water quality parameter including dissolved oxygen, pH,
water temperature, turbidity
Priority of procedure Comments Records
Location of the
sampling point
Equipment used for
measurement and for
sampling
— Values of temperature Method of
and oxygen unbiased (no measurement
exchange with air and no Values of
heating of the sample) measurement
— Risk: Value of Method of
temperature biased measurement
(heating of the sample) Values of
— Value of oxygen measurement
unbiased (no exchange
with air)
— Risks: Values of Method of
temperature and oxygen measurement
biased (exchange with air Values of
and heating of the measurement
sample)
10 Sample collection, contamination with environmental materials
To avoid contamination of water samples during collection, the following guidelines are provided.
— Samples should be collected from the upwind or upstream side of an anchored boat.
— Samples should be collected from the downwind side of a drifting boat.
— Where depth profile samples are collected, sampling should commence at the surface of the water column
and proceed downwards through the water column.
— When samples are collected during the course of wading, samples should be collected forward of the
waders path or upwind of the sampler.
— Samples should be collected in a manner that does not permit contamination by motor exhausts, dust,
debris and bottom sediments.
— Samples should be collected as to avoid collection devices or containers scraping against docks, poles,
preserved lumber and other infrastructure, boat hulls and antifouling coatings.
— Unless specified in the investigation plan, the sample should not include the surface film of the water or
floating layers.
— When sampling through ice, ice chips, ice-water slurry, meltwater and snow should not be allowed to enter
the sample container.
— When sampling waters covered in vegetation, care should be taken not to disturb the vegetation or allow
any of the vegetation to enter the sample container.
11 Rinsing the sampling equipment
All the equipment that comes in contact with the water should be rinsed, using water from the body of water
to be sampled. Rinse all the equipment used for sampling preferably up to three times.
If the analytical method requires the sample containers to be rinsed, remove the caps prior to taking the rinse
water, handling the caps in such a way that the interior surface does not become contaminated, preferably
holding them in one hand or keeping them in a polyethylene bag. Follow the instructions in ISO 5667--3 for
rinsing sampling containers. It is important that sample containers are not rinsed if they contain preservatives.
If using a rope or chain, pour some of the contents of the sample vessel rinse contents over the final metre of
the rope or chain to wash off all traces of previous samples. Remove as much excess liquid as possible by
shaking. Do not allow this part of the rope or chain to be re-contaminated by allowing it to come in contact
with the ground or any other surface. Similarly, rinse the end of the sampling pole if used.
12 Sampling surface or near-surface water with an open sampling device
12.1 General
Extra precautions should be taken for the analysis for volatile parameters including dissolved gases and
volatile organic compounds (see 14Clause 14).).
12.2 Sampling
If applicable, attach the sample container to a sampling pole or iron. Displace the floating layer by first making
a rotating movement with the container on the water surface. Rinse the sample container, preferably up to
three times, with surface water as required by the sampling protocol andor as may be directed by the
laboratory.
Submerge the sample container to the sampling depth, turn it around and allow the container to fill.
Ensure that bubbles are not collected during the sampling procedure. Hold the sample container at about a
45° angle to allow bubbles to escape the sample container.
If conducting direct sampling, seal the sample container and proceed to post-sampling requirements for the
samples.
If indirect water sampling is to be employed, rinse the filling devices and sample container as required by the
investigation plan. Fill the filling device and dispense the water sample into the sample container(s). Seal the
sample container.
12.3 Filling multiple containers
If filling more than a single sample container from a single sample collection is required, ensure that the
sample remains homogeneously mixed during filling of the sample container, by using, for example, a churn
sample splitter to dispense sample water among the sample containers.
Where several collections of water samples from a single sampling site are required to fill multiple sample
containers, either
a) a) combine the sample collections in a larger container, such as a churn sample splitter, before allocation
to sample containers, or
b) b) use sample water from individual collections to completely fill sample containers for independent sets
of inter-related parameters. For example, fill
Fill all sample containers needed for phosphorus fractions from the same collection, sample containers for
anions and cations may be filled from a second collection, sample containers for dissolved and suspended
heavy metals from a third collection.
Where depth or area composite samples are to be dispensed into multiple sample containers, mix the
constituent samples of the composite sample in a churn sample splitter or similar device prior to dispensing
sample water.
Samples should be collected and preserved in regardaccording to specific requirements with respect to the
method for which the samples have been taken.
13 Sampling with closed samplers
Closed samplers are typically used to sample volatile and non-volatile parameters in deeper waters, generally
greater than 1 m depth, and for volatile compounds in shallow waters. In general, horizontal closed samplers
are used in shallow or flowing waters while vertical samplers are used for deep, standing waters. Lower the
open sampling device slowly into the water column to the required depth, avoiding dynamic pressure,
allowing it to rinse as it descends. Seal the device when it has reached the desired depth and filled with sample
water. Remove it from the water. Rinse any filling devices and containers with sample water as required. Fill
containers as required. When multiple sample containers are to be filled or where multiple collections are to
be made, the procedures described in 12.312.3 should be followed. Samplers with lids that do not uncover the
entire cross-section area of the sampling tube while lowered in the water (e.g. Ruttner-sampler) are not
appropriate.
14 Sampling for volatile parameters
Sampling volatile parameters requires the use of closed sampling or pumping devices. Following collection of
the water sample with a closed sampling device, fill the sample containers directly from the device. Extend the
outlet of the device with a polytetrafluoroethylene (PTFE) tube long enough to reach the bottom of the sample
container. Position the PTFE outlet on the bottom of the sample container and fill it with the device. Fill the
container until it overflows. Then, remove the outlet from the container while the water is still flowing. Seal
the sample container immediately after removal of the outlet. The sample container should be completely
filled, without any air bubbles.
When using a pumping device to collect the water sample, pump sample water directly into the sample
container using an appropriate outlet tube as described above. Suction pumps should not be used for sampling
volatile compounds as volatile organics and dissolved gases can be removed from the sample.
Where double sampling containers (see 0Figure 1)) are used to sample volatile parameters in near-surface
waters, place the sampling containers at the required depth and wait until both containers have been
completely filled. Remove the PTFE stopper with inlet tube from the sampling container and seal this with a
ground-glass stopper. The sampling container should be completely filled, without any air bubbles.
15 Sampling through ice
Sampling through ice requires use of an ice chisel, auger or drill. Use a battery or hand-powered ice auger to
drill through the ice or an ice chisel when collecting samples for organics analyses, to reduce the possibility of
contamination of samples with gasoline, oil and combustion products. After drilling the hole, remove all ice
chips and snow from the hole and surrounding area prior to collection of the sample. Proceed with collection
as above but, if applicable, with recognition of the specific challenges of working under severe freezing
conditions. Strong gradients of parameters of interest can be present immediately below the ice surface. This
should be considered in developing the samp
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