ISO 15748-1:2002

Ships and marine technology - Potable water supply on ships and marine structures - Part 1: Planning and design

ISO 15748-1 applies to the planning, design and configuration of potable water supply systems on ships, stationary or floating marine structures and inland waterway vessels. It specifies the minimum requirements for potable water supply systems to be met in order to protect the potable water and to maintain its quality. ISO 15748-1 also provides hints on components to be used and on laying of the pipelines.

Navires et technologie maritime — Approvisionnement en eau potable sur navires et structures maritimes — Partie 1: Planification et conception

General Information

• Status: Published
• Publication Date: 29-May-2002
• ICS: 47.020.30 - Piping systems
• Technical Committee: ISO/TC 8/SC 3 - Piping and machinery
• Drafting Committee: ISO/TC 8/SC 3 - Piping and machinery
• Current Stage: 9093 - International Standard confirmed
• Start Date: 06-Jun-2024
• Completion Date: 13-Dec-2025

Relations

• Consolidates: ISO 7792-2:1988 - Plastics - Polyalkylene terephthalates - Part 2: Preparation of test specimens and determination of properties
• Effective Date: 06-Jun-2022

Overview

ISO 15748-1:2002 - "Ships and marine technology - Potable water supply on ships and marine structures - Part 1: Planning and design" sets out the minimum requirements for planning, design and configuration of shipboard and marine-structure potable water systems. It applies to ships, stationary or floating marine structures and inland waterway vessels, and focuses on protecting potable water quality, hygienic system layout and guidance on components and pipeline routing. (The transfer of potable water between facilities is excluded.)

Keywords: ISO 15748-1, potable water supply on ships, marine potable water, shipboard water systems, planning and design

Key Topics

• Scope and definitions: Terminology for potable water systems, heaters, tanks, ring lines, trunk lines, service fittings and more.
• Capacity & sanitary requirements: Sizing storage and conversion plants to ensure adequate potable water supply; potable water must be free of pathogens and acceptable in taste/appearance.
• System separation & backflow protection: Prohibition of connections to non-potable lines; recommendations for free-air lines, pipe disconnectors, backflow preventers and protective fittings.
• Materials and corrosion control: Requirements for hygienic, non‑contaminating materials and coatings suitable for potable water and resistant to anticipated stresses.
• Temperature limits: Definitions for cold water (5–25 °C) and hot water (50–90 °C, usually up to 60 °C); pressurized components rated for up to 90 °C; service fittings max 70 °C.
• Components & piping: Guidance on pipes, fittings, joints, pumps, potable water tanks, heaters, filters and sterilization plants.
• Layout, calculation & testing: Pipeline layout, hydraulic calculation principles (see Part 2), and procedures for testing and flushing pipelines.
• Informative annexes: Explanations, suggested pipe dimensions and filter inspection/maintenance guidance.

Keywords: pipeline layout, potable water tanks, sterilization of potable water, marine piping

Applications

ISO 15748-1 is practical for any marine project that requires safe, hygienic potable water systems:

• Design & engineering: Naval architects, marine engineers and ship designers use it for system planning and component selection.
• Shipyards & integrators: For installation, routing and commissioning of potable water systems.
• Operators & owners: To ensure compliance with hygiene and capacity requirements for accommodation and service areas.
• Equipment suppliers & class societies: For specifying pumps, heaters, filters, backflow preventers and tank arrangements.

This standard helps reduce contamination risk, ensure compliance with national potable water regulations and streamline maintenance/testing regimes.

Keywords: ship designers, marine engineers, potable water system design, backflow prevention

Related Standards

• ISO 15748-2 - Part 2: Method of calculation (hydraulic sizing)
• SOLAS 1974 - Safety of Life at Sea regulations (relevant maritime regulations)
• Referenced ISO standards on pipes and fittings (e.g., ISO 7-1, ISO 161-1, ISO 14726-1)

Using ISO 15748-1 together with Part 2 and applicable national rules ensures a robust, hygienic and code‑compliant shipboard potable water system.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15748-1
First edition
2002-05-01
Ships and marine technology — Potable
water supply on ships and marine
structures —
Part 1:
Planning and design
Navires et technologie maritime — Approvisionnement en eau potable sur
navires et structures maritimes —
Partie 1: Planification et conception

Reference number
©
ISO 2002
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ii © ISO 2002 – All rights reserved

Contents Page
Foreword.iv
1 Scope .1
2 Normative references.1
3 Terms and definitions .2
4 Capacity requirements.5
5 Sanitary requirements.5
6 Potable water supply systems .6
7 Technical requirements .7
8 Pipelines .7
9 Pipes and pipe dimensions .9
10 Fittings and pipe joints .9
11 Fittings.9
12 Protective fittings .10
13 Pumps.10
14 Potable water tanks.11
15 Potable water heating plants.13
16 Sterilization of potable water.16
17 Layout of piping.18
18 Calculation principles .21
19 Testing and flushing of pipelines .21
Annex A (informative) Explanations.22
Annex B (informative) Appropriate pipe dimensions .23
Annex C (informative) Inspection and maintenance of filters .25
Bibliography.26

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
The main task of technical committees is to prepare International Standards. Draft International Standards adopted
by the technical committees are circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 15748 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 15748-1 was prepared by Technical Committee ISO/TC 8, Ships and marine technology, Subcommittee SC 3,
Piping and machinery.
ISO 15748 consists of the following parts, under the general title Ships and marine technology — Potable water
supply on ships and marine structures:
— Part 1: Planning and design
— Part 2: Method of calculation
Annexes A, B and C of this part of ISO 15748 are for information only.

iv © ISO 2002 – All rights reserved

INTERNATIONAL STANDARD ISO 15748-1:2002(E)

Ships and marine technology — Potable water supply on ships
and marine structures —
Part 1:
Planning and design
1 Scope
This part of ISO 15748 applies to the planning, design and configuration of potable water supply systems on ships,
stationary or floating marine structures and inland navigation vessels.
This part of ISO 15748 specifies the minimum requirements for potable water supply systems to be met in order to
protect the potable water and to maintain its quality.
It also provides hints on components to be used and on laying of the pipelines.
NOTE The transfer of potable water and the regulations to be observed are not covered by this part of ISO 15748. The
transfer of potable water is subject to special regulations.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 15748. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 15748 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
ISO 7-1, Pipe threads where pressure-tight joints are made on the thread — Part 1: Dimensions, tolerances and
designation
ISO 65, Carbon steel tubes suitable for screwing in accordance with ISO 7-1
ISO 161-1, Thermoplastics pipes for the conveyance of fluids — Nominal outside diameters and nominal
pressures — Part 1: Metric series
ISO 228-1, Pipe threads where pressure-tight joints are not made on the threads — Part 1: Dimensions, tolerances
and designation
ISO 274, Copper tubes of circular section — Dimensions
ISO 426-2, Wrought copper-zinc alloys — Chemical composition and forms of wrought products — Part 2: Leaded
copper-zinc alloys
ISO 1127, Stainless steel tubes — Dimensions, tolerances and conventional masses per unit length
ISO 1635, Wrought copper and copper alloys — Round tubes for general purposes — Mechanical properties
ISO 4200, Plain end steel tubes, welded and seamless — General tables of dimensions and masses per unit
length
ISO 5620-1, Shipbuilding and marine structures — Filling connection for drinking water tanks — Part 1: General
requirements
ISO 14726-1, Ships and marine technology — Identification colours for the contents of piping systems — Part 1:
Main colours and media
1)
ISO 14726-2 , Ships and marine technology — Identification colours for the contents of piping systems — Part 2:
Additional colours for different media and/or functions
ISO 15748-2, Ships and marine technology — Potable water supply on ships and marine structures — Part 2:
Method of calculation
SOLAS 1974, International Convention for the Safety of Life at Sea, 1974
3 Terms and definitions
For the purposes of this part of ISO 15748, the following terms and definitions apply.
3.1
potable water supply system
system for the generation, treatment, transfer, conveyance, storage, transport and distribution of potable water
3.2
water treatment plant
equipment for treating potable water whilst maintaining potable water properties, e.g. using filters, dosage plants,
ion exchangers, disinfecting plants
3.3
potable water heaters
appliances used to heat potable water without affecting its properties for consumption apart from a change in
temperature, e.g. continuous-flow water heaters, storage heaters
3.4
apparatus
collective term for technical installations making use of and/or transforming potable water
EXAMPLE
 distillation and sterilization apparatus;
 large-scale cooking equipment, dosage plant;
 pressurized water reservoirs, water heaters;
 dishwashers, coffee machines, as well as devices of all kinds forming part of the potable water system or connected
temporarily or permanently to it, except for supply and circulating pumps.
3.5
water
collective term for all types of water used for water supply

1) To be published
2 © ISO 2002 – All rights reserved

3.6
raw water
untreated water
NOTE Raw water and sea water are considered equivalent.
3.7
freshwater
water originally intended for human consumption and use on board as potable water but also used for certain
technical purposes and for sanitary-hygienic needs
3.8
potable water
water suitable for human consumption and use in compliance with the quality requirements laid down in the
applicable statutory provisions, defined in this part of ISO 15748 as:
a) water from a central public potable water supply;
b) water converted from sea water by evaporation at temperatures exceeding 80 °C;
c) water converted from sea water by evaporation at temperatures below 80 °C, and which has additionally been
sterilized;
d) water generated by reverse osmosis;
e) hot potable water heated in suitable water heaters.
3.9
cold water
cold potable water at temperatures between 5 °C and 25 °C
NOTE The upper temperature limit may be higher e.g. in the tropics.
3.10
hot water
hot potable water at temperatures between 50 °C and 90 °C, usually up to 60 °C
3.11
mixed water
hot and cold potable water mixed by means of a mixer tap
3.12
potable water line
pipeline exclusively carrying potable water
3.13
supply line
entire potable water pipeline system downstream of the discharge (supply) pump
3.14
water main
section of piping between the discharge pump and the point where the cold water line branches off from the line
leading to the central water heater
3.15
distribution line
section of the supply line downstream of the watermain
3.16
ring line
distribution line providing bidirectional water supply by way of loop-type installation
3.17
hot-water ring line
distribution line for unidirectional supply only with water circulation by means of a circulating pump to feed back
unused hot water to the water heater
3.18
circulating line
section of the cold/hot-water ring line without dispensing point, via which unused cold water is fed back to the
suction side of the supply pump or unused hot water is fed back to the water heater
3.19
trunk line
riser
vertical section of the supply line branching off from a distribution line
NOTE Deck lines and dispensing lines branch off from trunk lines.
3.20
deck line
section of the supply line branching off from the trunk line within one deck
3.21
service line
single feed line
section of the supply line leading from the deck line to the consumer
3.22
pump discharge line
discharge line downstream of the discharge outlet of a pump
3.23
pump return line
line through which water is fed to the pump
3.24
service fitting/outlet fitting
fitting for shutting off, releasing and controlling the volume flow at the end of a supply line, the outlet side thereof
being in accordance with the service function, e.g. equipment valve, outlet valve, flush valve, mixer tap
3.25
safety fitting
fitting to protect system parts against inadmissible pressure and temperature transgressions, e.g. safety valves
3.26
protective fitting
fitting to protect the water characteristics in the piping system, e.g. vacuum breakers in connection with non-return
valves, pipe disconnectors
3.27
filter
device for extraction of solid matter from potable water
3.28
calculation flow
assumed flow at the service fitting taken as calculation basis:
 
VV=+V 2
()
Rmin 0
4 © ISO 2002 – All rights reserved

where

V is the calculation flow, expressed in litres per second;
R

V is the minimum flow, expressed in litres per second;
min

V is the peak flow, expressed in litres per second.
3.29
sum flow
sum of the calculation flows for all water-consuming units served via one cross-section
3.30
peak flow
flow decisive for hydraulic calculation, taking into consideration probable simultaneous water withdrawals during
operation
3.31
closed continuous flow heater
water heater resistant to pressure wherein the water is heated whilst passing the heater, with or without storage
3.32
open storage heater
pressureless water heater, heating and storing water in a container which is part of the storage heater
4 Capacity requirements
On ships, marine structures and inland waterway craft, pure potable water shall always be available in sufficient
quantity. The potable water supply system shall be sized and designed accordingly.
Depending on needs, sufficiently sized potable water storage tanks and/or plants for the conversion of sea water to
potable water shall be provided.
Any accommodation areas on ships and marine structures that are not provided with a dispensing facility from a
central potable water supply shall be equipped with a sufficiently sized potable water container.
5 Sanitary requirements
5.1 Potable water
The quality of the potable water shall be such that its consumption and use will not affect human health, particularly
as far as pathogenic microorganisms are concerned; i.e. potable water
 shall be free of pathogenic microorganisms;
 shall be as sterile as possible;
 should be palatable (it shall be colourless, clear, cool, odourless and acceptable with respect to taste);
 may only contain traces of dissolved minerals.
As far as health considerations are concerned, the potable water characteristics shall comply with the potable
water regulations stated by the authorized national governmental bodies.
5.2 Protection of the potable water, maintenance of the potable water quality
5.2.1 Potable water supply systems shall be fitted with a means of sterilizing water transferred from land-based
facilities or water stored on board for a prolonged period of time.
5.2.2 It is not permissible to connect potable water lines to lines or facilities carrying water which is not potable
(e.g. cooling freshwater lines); there shall be a hygienically reliable separation between these lines, which may be
achieved, e.g.
 by means of a free air line;
 by means of an indirect connection via the storage units (water supply via a free air line);
 by means of a pipe disconnector;
 by means of a back flow preventer.
5.2.3 Potable water dispensing points where a backflow of water is possible shall be secured by means of
protective fittings in accordance with 3.26.
5.2.4 Any material, auxiliary material or protective coating used shall be safe from a hygienic and physiological
point of view, and shall be sufficiently resistant to any physical, chemical or corrosive stress to be anticipated. It
shall not release any substances which may influence the digestibility, taste, smell or colour of the potable water. If
applicable, the coating shall comply with the requirements of national authorities.
Pressurized components shall not be negatively influenced by water temperatures of up to 90 °C. For service
fittings the maximum temperature is 70 °C.
5.2.5 Internal corrosion shall be prevented as far as possible by selecting and using materials that are suitable
for potable water (cold or hot) and that are compatible with each other.
5.2.6 Compressed-air cushions directly contacting the water surface inside the pressurized reservoir shall not
impair the quality of the potable water.
5.2.7 Plastics and other non-metallic materials shall conform to the requirements and recommendations
concerning the suitability of these materials to potable water, stated by the authorized national bodies.
6 Potable water supply systems
A potable water supply system includes all facilities, piping and apparatus serving to transfer, store, treat, transport
or dispense potable water. Also included in this definition are facilities serving to produce potable water, e.g.
distillation from sea water.
If the potable water is conveyed through apparatus and facilities that will impair its alimentary quality as defined by
the regulations, the potable water system terminates at the assigned safety fitting. The following components may
be included in potable water supply systems:
 potable water tanks;
 transfer, operating and service lines;
 pumps;
 pressurized water reservoirs;
 potable water heaters;
6 © ISO 2002 – All rights reserved

 potable water treatment plants;
 potable water distillation plants;
 fittings (shut-off, safety, protection and supply or outlet fittings);
 measuring and control devices. Figure 1 shows an example of realization of a potable water supply system.
7 Technical requirements
7.1 Associated regulations
In planning the installation of potable water supply systems, the following regulations and directives shall be
observed:
 rules for classification and construction of seagoing ships stated by the relevant classification society;
 technical rules given by a marine employer's liability insurance (if applicable);
 nationally-stated requirements concerning potable water systems.
7.2 Identification marking
Fittings and appliances shall be marked legibly and permanently with the manufacturer's designation or name in
order to readily provide identification of the product at any time. The marking shall comply with the applicable
regulations.
7.3 Pressure and temperature
7.3.1 For safety reasons all components shall be designed to sustain the same working pressures; this pressure
shall comply with the highest set pressure of a safety valve within the system.
7.3.2 Pressure surges and drops occurring during operation shall not exceed the applicable limits (see
ISO 15748-2). This, and the admissible flow rates, shall be taken into consideration when selecting the fittings.
7.3.3 Temperature increases in cold water pipes shall be prevented by suitable means; see explanations in
annex A.
7.3.4 The water temperature in hot water pipes shall be at least 50 °C; see explanations in annex A.
8 Pipelines
8.1 Air pipes, filling pipes and overflow pipes
For air pipes, filling pipes and overflow pipes see the requirements of the relevant classification society. The filling
connection for drinking water tanks shall be in accordance with ISO 5620-1.
8.2 Sounding pipes
For sanitary reasons, sounding pipes for operational gauging in potable water tanks are not permitted. To check
the level, fluid level gauges or devices for measuring tank contents shall be installed.
Key 9 Potable water supply pump
1 Accommodation area with showers/W.C. 10 Pressure tank
2 Commissary area 11 Technical load
3 Engine room 12 Pipe disconnector
4 Shower/W.C. 13 Sterilization
5 Filling connection for potable water tanks (see ISO 5620-1) 14 Water heater
6 Potable water generator 15 Heating medium
7 Drinking water tank 16 Cold water circulating pump
8 Sea chest 17 Hot water circulating pump
Figure 1 — Example of a potable water supply system on a ship with four superstructure decks
8 © ISO 2002 – All rights reserved

9 Pipes and pipe dimensions
For potable water piping systems the pipes and pipe dimensions given in Tables B.1 to B.3 may be used taking the
installation and operating instructions, and the respective regulations devised by the cognizant authorities into
consideration.
10 Fittings and pipe joints
10.1 Fittings and flanged joints
Taking installation and operating instructions into consideration, the fittings and flanged joints to be selected for the
pipes listed in Tables B.1 to B.3 may be used without special proof of suitability.
10.2 Threaded joints
Whitworth threads shall conform to ISO 7-1.
Threads conforming to ISO 228-1 may only be used if the sealing effect is achieved by a gasket being pressed
between the front face of the bell connection and a collar on the externally threaded section.
10.3 Welded, soldered or bonded joints
10.3.1 Steel pipes may only be welded on condition that the internal protective coating remain undamaged.
Brazed joints on steel pipes are only permissible if they are executed conformant with the instructions issued by the
manufacturer of the solder [the development of hard zinc layers with reduced corrosion resistance in the soldering
area (heat affected zone) shall be pointed out].
10.3.2 Copper tubes shall only be welded if their wall thickness is W 1 mm.
10.3.3 Stainless steel pipes shall be worked in accordance with the manufacturer's recommendations.
10.3.4 For the fabrication of CuNiFe pipes see available national standards or the manufacturer's recommen-
dations.
10.3.5 PVC pipes shall be bonded and shall not be welded.
10.3.6 For welded joints of high-density and low-density polyethylene pipes (PE-HD and PE-LD) see available
national standards or the manufacturer's recommendations.
10.3.7 Brazing and soldering compounds shall not contain lead.
11 Fittings
11.1 General
Sanitary fittings for supply lines shall conform to the requirements of national authorities (if applicable).
11.2 Water-saving fittings
The fittings to be used shall be exclusively of the water-saving kind and, where appropriate, flow restrictors shall be
installed.
11.3 Non-return valves
Fittings for cold and heated potable water shall have a common outlet only if this outlet cannot be closed or if
crossing over of the warm potable water into the cold water line is prevented by means of adequate functional
parts; these may be approved non-return valves.
11.4 Protection against scalding
To prevent scalding, hot water showers should be fitted with safety devices (e.g. thermostatic mixer taps) limiting
the temperature of the heated water or the mixed water to 45 °C.
11.5 Materials
The following materials may be regarded as safe with respect to sanitary considerations and corrosion resistance.
Other materials may only be used if they are of identical or better quality than the ones listed:
 wrought and cast stainless steels;
 materials such as CuSn10, CuPb5Sn5Zn5 and GKCuZn40Pb;
 materials specified in ISO 426-2, namely CuZn38Pb2.
11.6 Lubricants
Lubricants shall be suitable for potable water supply systems.
12 Protective fittings
Potable water supply systems shall be fitted with approved non-return valves downstream of the supply pump or
water reservoir in order to prevent water from flowing back into the potable water tank.
Only protective fittings carrying the test lable of the national approving authority shall be used (if applicable).
13 Pumps
13.1 Self-priming pumps
Self-priming pumps shall be installed if the potable water tank is located below the installation level of the supply
pump.
13.2 Pump capacity
Dimensioning of the pump capacity shall be such that there is still sufficient flow pressure despite maximum water
consumption (for determination of the peak consumption see 8.3 of ISO 15748-2:—).
For projects with high peak consumption rates (e.g. passenger ships, marine structures) installation of two or more
supply pumps is recommended.
13.3 Circulating pumps
Circulating pumps shall be installed if reasons given in 17.2.7 or in A.2 are to be considered.
10 © ISO 2002 – All rights reserved

13.4 Filters
Filters shall be installed in the suction line of the supply pump in order to clear the potable water of undissolved
matter. They shall comply with requirements of the national authorities, if available, and shall undergo minimum
maintenance in accordance with annex C.
13.5 Shut-off fittings and pressure gauges
Shut-off fittings and pressure gauges shall be fitted upstream of the intake as well as downstream of the discharge
of the supply pumps.
13.6 Controllable non-return valves
With pumps switched in parallel, these valves shall be furnished on the discharge side.
14 Potable water tanks
14.1 General requirements
Potable water tanks may be a part of the ship's structure with minimum required framing (except double-bottom
tanks, fore-peak and aft-peak tanks) or be installed as separate (inserted) tanks. Tanks, which are part of the ship's
structure shall not have a common bulkhead (ceiling, deck) with tanks destined for other media.
Tanks shall be made of corrosion-resistant steel or shall have an anticorrosive coating. Steel water tanks shall be
protected against corrosion by a galvanic or varnished coating.
Zinc coating shall not have flaws. Surfaces that come into contact with water shall not have even refurbished flaws.
Surfaces shall be free of any residues such as zinc oxide or soldering flux and meet the requirements laid down in
5.2.4.
On sea-going vessels and marine structures, it is recommended that two potable water tanks be installed for good
reliability of the water supply system.
Potable water tanks shall be disposed in the rooms that have no sources of heat emission and dirt. In exceptional
cases if, for technical reasons, it is found impossible to satisfy this requirement, it is admissible to place them in
rooms with heat emission, but then effective action for water protection against heating shall be taken.
Potable water storage tanks shall have tightly closable hand-holes for repair and cleaning.
Hand-holes shall be set and constructed in such a way that there is no soiling of water through them. Hand-holes
shall be made preferably on side walls of tanks. For prevention of an occasional soiling, the hand-holes arranged
on decks, may have coamings at least of 200 mm above deck.
For drainage of water residues and deposits, drainage cocks, plugs etc. should be provided preferably at the low
part of inserted tanks and other tanks with arrangement of inclinations of tank bottoms.
Reinforcing ribs of inserted potable water tanks shall be provided on the outside.
Tanks shall be equipped with air pipes led out on the deck and ending with special facilities that prevent admission
of sea water. The end of air pipe led out on the deck, shall be at least 400 mm above deck level and be sited in
places which eliminate the possibility of soiling and flooding with sea water. Air pipes bores shall be at least 32 mm
(for crafts and
...