ASTM D1291-17(2023)

Standard Practice for Estimation of Chlorine Demand of Water

SIGNIFICANCE AND USE
5.1 Chlorine is added to potable water, waste water, and industrial water for a variety of purposes. Some of these purposes are:  
5.1.1 To eliminate or reduce the growth of microorganisms in water,  
5.1.2 To destroy or modify decomposable organic substances so as to reduce the biochemical oxygen demand of the water,  
5.1.3 To eliminate or reduce taste, odors, and color in the water,  
5.1.4 To separate grease in waste water by eliminating the protective colloidal effect of proteins present, and  
5.1.5 To destroy or modify substances in the waste water that react directly by oxidation, such as ammonia, cyanates, cyanides, ferrous iron, nitrites, phenol, phosphorus, sulfides, sulfites, thiocyanates, and other oxidizable constituents.  
5.2 It is important to avoid over-chlorination in order to minimize chemical consumption, meet restrictions specified by regulatory agencies, and minimize equipment degradation.
SCOPE
1.1 This practice provides a means of estimating the quantity of chlorine required to be added to a unit volume of water to accomplish a predetermined treatment objective or to completely react with all chlorine reactable substances in the water, or both.  
1.2 Temperature, pH, and initial chlorine dosage are all variables in estimating the optimum chlorination practice. The effects of these variables can be evaluated using this practice.  
1.3 Chlorine residual is determined using Test Method D1253.  
1.4 This practice is applicable to all types of water in which the stated treatment objective can be evaluated or residual chlorine can be measured, or both.  
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement, see 7.5.1.  
1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Oct-2023
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.03 - Sampling Water and Water-Formed Deposits, Analysis of Water for Power Generation and Process Use, On-Line Water Analysis, and Surveillance of Water

Relations

• Replaces: ASTM D1291-17 - Standard Practice for Estimation of Chlorine Demand of Water
• Effective Date: 01-Nov-2023
• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D1129-13(2020)e1 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020

Overview

ASTM D1291-17(2023), Standard Practice for Estimation of Chlorine Demand of Water, provides a systematic method for estimating the required chlorine dosage to achieve specified treatment objectives or to completely react with all chlorine-reactable substances in various water types. Developed by ASTM International, this standard underpins effective water treatment, disinfection, and process optimization in potable, industrial, and wastewater systems. Proper estimation of chlorine demand is vital for efficient chemical use, regulatory compliance, and maintaining equipment longevity.

Key Topics

• Chlorine Demand Determination: This standard outlines procedures to assess how much chlorine is needed to reach specific goals, such as disinfection, odor control, or oxidation of contaminants in water.
• Variables Affecting Chlorination: It recognizes the importance of factors such as water temperature, pH, and initial chlorine dosage, all of which influence chlorine demand and treatment outcomes.
• Sample Analysis: The practice uses established methods, such as ASTM D1253, for measuring residual chlorine. Precise determination of residual chlorine enables accurate calculation of chlorine demand.
• Treatment Objectives: Chlorine may be used to:
  • Disinfect water by reducing microorganisms
  • Oxidize organic substances and reduce biochemical oxygen demand (BOD)
  • Eliminate or reduce taste, odor, and color issues
  • Remove or oxidize industrial contaminants such as ammonia, phenols, cyanides, and various oxidizable substances
  • Disrupt protective colloidal effects in wastewater to improve grease removal
• Avoidance of Over-Chlorination: The standard emphasizes the importance of preventing excessive chlorine application to optimize chemical consumption, meet regulatory standards, and protect equipment from degradation.

Applications

The ASTM D1291-17(2023) standard is applicable to a range of water treatment scenarios, supporting operators, engineers, and analysts in:

• Potable Water Treatment: Assisting in determining the chlorine dosages needed for effective disinfection, ensuring safe drinking water while avoiding harmful byproducts.
• Wastewater Treatment: Estimating chlorine requirements for reducing BOD, removing undesirable substances, and meeting effluent quality standards.
• Industrial Water Treatment: Guiding applications in cooling towers, process waters, and recycling systems where specific water quality objectives must be met.
• Regulatory Compliance: Helping treatment facilities remain within chemical usage limits set by environmental and public health authorities.
• Process Optimization: Enabling informed decisions about how much chlorine is necessary to achieve treatment objectives, enhancing operational efficiency and cost control.

Related Standards

When implementing or referencing ASTM D1291-17(2023), consider the following related ASTM standards:

• ASTM D1193: Specification for reagent water used in laboratory analyses
• ASTM D1253: Test method for measuring residual chlorine in water
• ASTM D1293: Test methods for pH measurement of water
• ASTM D3370: Sampling practices for water from flowing process streams

By integrating these standards, water professionals can ensure accuracy in sampling, reagent preparation, and analytical measurement, leading to reliable and reproducible results in chlorine demand estimation.

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Keywords: chlorine demand, water treatment, potable water, wastewater, industrial water, residual chlorine, ASTM D1291, chlorination, disinfection, oxidation, chemical dosage, water quality, regulatory compliance, pH, temperature, ASTM standards

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D1291 − 17 (Reapproved 2023)
Standard Practice for
Estimation of Chlorine Demand of Water
This standard is issued under the fixed designation D1291; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D1193 Specification for Reagent Water
D1253 Test Method for Residual Chlorine in Water
1.1 This practice provides a means of estimating the quan-
D1293 Test Methods for pH of Water
tity of chlorine required to be added to a unit volume of water
D3370 Practices for Sampling Water from Flowing Process
to accomplish a predetermined treatment objective or to
Streams
completely react with all chlorine reactable substances in the
water, or both.
3. Terminology
1.2 Temperature, pH, and initial chlorine dosage are all
3.1 Definitions:
variables in estimating the optimum chlorination practice. The
3.1.1 For definitions of terms used in this standard, see
effects of these variables can be evaluated using this practice.
Terminology D1129.
1.3 Chlorine residual is determined using Test Method
3.2 Definitions of Terms Specific to This Standard:
D1253.
3.2.1 chlorine demand, n—the amount of chlorine that must
1.4 This practice is applicable to all types of water in which
be added to a unit volume of water under specified conditions
the stated treatment objective can be evaluated or residual
of pH, temperature, and contact time to completely react with
chlorine can be measured, or both.
all chlorine-reactable substances in the water.
1.5 The values stated in SI units are to be regarded as
3.2.1.1 Discussion—It is defined as the difference between
standard. No other units of measurement are included in this
the amount of chlorine applied and the amount of free chlorine
standard.
remaining at the end of the contact period.
1.6 This standard does not purport to address all of the
3.2.2 chlorine requirement, n—the amount of chlorine that
safety concerns, if any, associated with its use. It is the
must be added to a unit volume of water under specified
responsibility of the user of this standard to establish appro-
conditions of pH, temperature, and contact time to achieve the
priate safety, health, and environmental practices and deter-
objectives of chlorination.
mine the applicability of regulatory limitations prior to use.
For a specific hazard statement, see 7.5.1. 4. Summary of Practice
1.7 This international standard was developed in accor-
4.1 Known amounts of chlorine are added to a series of
dance with internationally recognized principles on standard-
500 mL aliquots of sample. The treated sample aliquots are
ization established in the Decision on Principles for the
permitted to stand for a specified contact time (or a variety of
Development of International Standards, Guides and Recom-
different specified contact times) under specified conditions of
mendations issued by the World Trade Organization Technical
pH and temperature. At the end of the contact time, the sample
Barriers to Trade (TBT) Committee.
aliquots are either analyzed for chlorine content by Test
Method D1253 or subjected to whatever evaluative technique
2. Referenced Documents
is required to establish accomplishment of the treatment
2.1 ASTM Standards:
objective, or both.
D1129 Terminology Relating to Water
5. Significance and Use
This practice is under the jurisdiction of ASTM Committee D19 on Water and
is the direct responsibility of Subcommittee D19.03 on Sampling Water and
5.1 Chlorine is added to potable water, waste water, and
Water-Formed Deposits, Analysis of Water for Power Generation and Process Use,
industrial water for a variety of purposes. Some of these
On-Line Water Analysis, and Surveillance of Water.
purposes are:
Current edition approved Nov. 1, 2023. Published November 2023. Originally
5.1.1 To eliminate or reduce the growth of microorganisms
approved in 1953. Last previous edition approved in 2017 as D1291 – 17. DOI:
10.1520/D1291-17R23.
in water,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
5.1.2 To destroy or modify decomposable organic sub-
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
stances so as to reduce the biochemical oxygen demand of the
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. water,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1291 − 17 (2023)
5.1.3 To eliminate or reduce taste, odors, and color in the 10 g to 100 g of available chlorine per litre with water to
water, provide a solution containing from 0.5 mg to 10 mg available
5.1.4 To separate grease in waste water by eliminating the chlorine per litre, depending upon the maximum expected
protective colloidal effect of proteins present, and chlorine requirement for the sample. This solution must be
5.1.5 To destroy or modify substances in the waste water standardized before use.
that react directly by oxidation, such as ammonia, cyanates,
7.5.3 Standardize the chlorine water or sodium hypochlorite
cyanides, ferrous iron, nitrites, phenol, phosphorus, sulfides,
solution, standard, as follows:
sulfites, thiocyanates, and other oxidizable constituents.
7.5.3.1 Transfer 10 mL of the solution to be standardized to
a porcelain dish.
5.2 It is important to avoid over-chlorination in order to
7.5.3.2 Add 10 mL of acetic acid (1 + 1) (see 7.3) and
minimize chemical consumption, meet restrictions specified by
10 mL of potassium iodide solution (see 7.8).
regulatory agencies, and minimize equipment degradation.
7.5.3.3 Titrate with sodium thiosulfate solution (0.10 N)
6. Apparatus
(see 7.11) until the yellow color of the liberated iodine is
almost discharged.
6.1 All of the apparatus listed in Test Methods D1293 and
7.5.3.4 Add 1 mL of starch indicator solution (see 7.12) and
D1253 may be required. Any other apparatus necessary to
continue the titration to a colorless endpoint.
carry out the final evaluation of the effects of chlorination will
be required. 7.5.3.5 Calculate the concentration of available chlorine as
follows:
7. Reagents and Materials
A × B × 35.45
Available chlorine, mg/mL 5
7.1 Purity of Reagents—Reagent grade chemicals shall be
C
used in all tests. Unless otherwise indicated, it is intended that
where:
all reagents shall conform to the specifications of the Commit-
A = sodium thiosulfate solution, standard, mL,
tee on Analytical Reagents of the American Chemical Society,
B = normality of sodium thiosulfate solution, standard, and
where such specifications are available. Other grades may be
C = chlorine solution titrated, mL.
used, provided it is first ascertained that the reagent is of
sufficiently high purity to permit its use without lessening the
7.6 Hydrochloric Acid (1 + 1)—Mix equal volumes of con-
accuracy of the determination.
centrated HCl (sp gr 1.19) and water.
7.2 Purity of Water—Unless otherwise indicated, references
7.7 Potassium Dichromate Solution (0.100 N)—Dissolve
to water shall be understood to mean reagent water conforming
4.904 g of anhydrous potassium dichromate (K Cr O ) of
2 2 7
to Specification D1193, Type III, which has been rendered
primary standard quality in water and dilute to 1000 mL in a
chlorine demand-free. Chlorine demand can be removed by
volumetric flask.
treating with excess chlorine and allowing this treated solution
7.8 Potassium Iodide Solution (50 g/L)—Dissolve 50 g of
to stand in sunlight for several hours to destroy the chlorine
potassium iodide (KI) in 1 L of freshly boiled and cooled water.
residuals. Test Method D1253 may be used to assure complete
Add 1 g of sodium bicarbonate (NaHCO ) to stabilize the
destruction of these residuals.
solution. Store in an amber bottle and avoid direct exposure to
7.3 Acetic Acid Solution (1 + 1)—Mix equal volumes of
sunlight.
glacial acetic acid and water.
7.9 Sodium Hydroxide Solution (10 g/L)—Dissolve 10 g of
7.4 Calcium Hydroxide Solution (10.7 g/L)—Weigh 10.7 g
sodium hydroxide (NaOH) in water and dilute to 1 L.
of 100 % hydrated lime, Ca(OH) , and suspend in water. Dilute
(Warning—Heat is generated when dissolving sodium hy-
the suspension to 1 L. Shake well each time before using.
droxide in water.)
7.5 Chlorine Solution, Standard—Prepare one of the stan-
7.10 Sodium Thiosulfate Solution, Standard (0.10 N)—
dard solutions described in 7.5.1 and 7.5.2; standardize as
Transfer 25 g of sodium thiosulfate pentahydrate (Na S O ·
2 2 3
described in 7.5.3.
5H O) to a 1 L volumetric flask containing about 800 mL
7.5.1 Chlorine Water—Pass chlorine gas through reagent
water. Dissolve the compound in the water by shaking and
water until the solution contains from 0.5 mg ⁄L to 10.0 mg ⁄L
periodic inversion. Add 1 g of sodium carbonate (Na CO ) and
2 3
Cl . (Warning—Use a slow rate of addition and carry out the
dissolve. Dilute the solution to 1 L with water.
operation under a hood. Store in a glass stoppered amber bottle
7.10.1 Standardize the Sodium Thiosulfate Solution—Add
and standardize daily before use.)
70 mL of water to a porcelain dish, and add, with constant
7.5.2 Sodium Hypochlorite Solution, Standard—Dilute a
stirring, 1 mL of concentrated sulfuric acid (H SO ), 10.0 mL
2 4
commercial sodium hypochlorite or bleach solution containing
of 0.100 N K Cr O , and 20 mL of potassium iodide solution
2 2 7
(see 7.8). P
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