II. Domestic/Building Water System Disinfection

San Diego State University
Environmental Health and Safety Department

Water Main and Building Water Disinfection and Testing

B. General Requirements

Installation of all plumbing fittings and valves necessary for flushing and chlorination shall be done by the contractor.

Chlorination and final flush shall be done by a commercial disinfecting company which has demonstrated its ability, equipment, and knowledge of chlorination procedures in compliance with AWWA §C651-05 or the most current. Contractor shall submit the name of the proposed company for approval. Approvals shall be given by Environmental Health & Safety (EH&S) on each specific job. Notify EH&S, on the Attachment 1: Chlorination Notification Form, at least 5 working days prior to the date of chlorination. Provide EH&S the Attachment 2: Chlorination Report, indicating the date of chlorination, lines disinfected, method of chlorination, amount and type of disinfection used, concentration applied, chlorine residual attained in system, holding time, chlorine residual after retention period, date of flushing, and chlorine residual concentration after flushing.

Bacteriological analysis shall be done by a state certified testing laboratory for drinking water quality. Disinfecting company shall submit the name of the proposed laboratory as well as the proposed number and location of samples for approval. Approval shall be given by Environmental Health & Safety on each specific job. Notify EH&S, on the Attachment 3: Bacteriological Sampling Notification Form, at least 3 working days prior to the date of sampling. Provide EH&S the Bacteriological Report, indicating date of sampling, sample location, presence or absence of coliform organism (total and fecal coliform), and heterotrophic plate count. A microbial laboratory analysis report is acceptable as Bacteriological Report.

All fixtures to be served by the potable water system shall be in place at the time of chlorination.
Injection Port: provide and install, within 3 feet of the supply main, an injection port for introducing the chlorine solution. An upstream gate valve or other means to control water flow, while connecting chlorination equipment, is required.
There shall be no dead-end sections in the system exceeding 3 feet in length. All branches within the system shall lead to an outlet for bleeding and flushing.
Prior to injection, it is necessary to place signs on each fixture being treated in order to prevent persons from using heavily chlorinated water. Sign shall read “Heavily chlorinated water — do not use.”

D. Chlorination Procedures

There are two options available to companies performing the chlorination, the “24 hour hold” method and the “3 hour scrub” method. In general, the “24 hour hold” is the method of choice, but the “3 hour scrub” can be used on small jobs where time is crucial and the chlorinators skills are highly satisfactory. The following is a description of the two procedures:

a. The chlorine shall be introduced at such a rate into the supply stream to provide a uniform concentration of chlorine in the entire system. The concentration is to be sufficient to maintain a 25-50 ppm chlorine level at each fixture after a hold period of 24 hours. In order to minimize corrosive effects on the plumbing system, the chlorine residual shall not exceed 150 ppm at any time.

b. During injection, the chlorine shall be drawn through each outlet and fixture in the system. In order to expedite the chlorination of hot water systems, it is usually best to drain the water heater prior to beginning the chlorine injection. Then chlorine of proper concentration is found at each outlet, all valves shall be closed, including the service cock and supply valve. In order to prevent tampering with the system during the 24 hour hold period, it is recommended that signs be placed, fixtures be taped, and/or valve handles be removed.

c. Testing for the residual concentration in the system at the end of the 24 hours will be done by EH&S. No water shall be released from the system until these samples are taken. A minimum concentration of 10-25 ppm of chlorine must be found at all chosen sampling points.

d. After satisfactory compliance with the 10-25 ppm for the 24 hour residual requirement, the system shall be flushed at a relatively high velocity to remove the injected chlorine. Evidence of proper flushing will be reduction of chlorine concentration in the system to no more than 0.5 ppm above that in the normal supply.

e. When EH&S has approved the flushing process, the entire system shall be resecured for a holding period of not less than 3 days prior to taking samples for bacteriological analysis. During this holding period, it is again recommended that all valves be closed, taped, and handles removed to maintain chlorination integrity and prevent repetition of the entire process.

a. The chlorine shall be introduced at such a rate into the supply stream to provide a uniform 100 ppm concentration during an entire 3 hour time period with all fixtures flowing. A substantial flow is required at all fixtures; dripping is not acceptable. In order to minimize corrosive effects on the plumbing system, the chlorine residual shall not exceed 150 ppm at any time.

b. In order to expedite the chlorination of hot water systems, it is usually best to drain the water heater prior to beginning the chlorine injection.

c. Testing for chlorine concentration shall be frequently done by the personnel performing the chlorination and at least once by EH&S.

d. After completion of the “3 hour scrub,” the system shall be flushed at a relatively high velocity to remove the injected chlorine. Evidence of proper flushing will be reduction of chlorine concentration in the system to no more than 0.5 ppm above that in the normal supply.

e. When EH&S has approved the flushing process, the entire system shall be secured for a holding period of not less than 3 days prior to the taking samples for bacteriological analysis. During this holding period, it is recommended that all valves be closed, taped, and handles removed to maintain chlorination integrity and prevent repetition of the entire process.

E. Preliminary Approval and Bacteriological Sampling

When EH&S has approved the flushing process, the entire system shall be secured for a holding period of not less than 3 days prior to taking samples for bacteriological analysis. During this holding period, it is recommended that all valves be closed, taped, and handles removed to maintain chlorination integrity and prevent repetition of the entire process.

At the completion of the 3 day hold period, bacteriological water samples are taken under the direction of EH&S. The number of necessary samples and sampling locations shall be determined by EH&S. Samples shall be taken from representative locations of the building, particularly drinking water fountains, eyewash stations, etc. A control sample shall also be taken from a building nearby that receives water from the same water main. The domestic water system cannot be used until the effectiveness of the chlorination procedure on the system has been determined by EH&S.

If initial bacteriological samples are unsatisfactory, the new building water system should be reflushed and additional samples collected and analyzed. If any of the check samples are also unsatisfactory, the new building water system must be rechlorinated, reflushed, and resampled until satisfactory results are achieved.

F. Bacteriological Analysis

Water testing must be done by a state certified testing laboratory approved by EH&S. Sample bottles must be provided by the laboratory and analysis must be done in accordance with APHA “Standard Methods.” The laboratory shall report the presence of any E. coli bacteria in a 100 ml sample (this must be negative to be acceptable) and the total plate count of bacteria per ml of the sample (this count must be less than 100 or equal to the supply to be acceptable)

G. Final Approval

Upon satisfactory completion of all disinfection procedures designated by EH&S and receipt of acceptable bacteriological results, written approval of the system will be provided to the responsible contractor (Attachment 4: Chlorination and Bacteriological Testing Verification and Approval). Failure to fully comply with the above procedures may result in a requirement to repeat chlorination of the system until the specified standards are met.


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	Environmental Health & Safety Potable (Drinking) Water San Diego State University Environmental Health and Safety Department Water Main and Building Water Disinfection and Testing II. Domestic/Building Water System Disinfection A. All new, remodeled or repaired potable water systems must be disinfected prior to use. All disinfection procedures must be conducted under the direction of the SDSU Environmental Health & Safety Department. B. General Requirements Installation of all plumbing fittings and valves necessary for flushing and chlorination shall be done by the contractor. Chlorination and final flush shall be done by a commercial disinfecting company which has demonstrated its ability, equipment, and knowledge of chlorination procedures in compliance with AWWA §C651-05 or the most current. Contractor shall submit the name of the proposed company for approval. Approvals shall be given by Environmental Health & Safety (EH&S) on each specific job. Notify EH&S, on the Attachment 1: Chlorination Notification Form, at least 5 working days prior to the date of chlorination. Provide EH&S the Attachment 2: Chlorination Report, indicating the date of chlorination, lines disinfected, method of chlorination, amount and type of disinfection used, concentration applied, chlorine residual attained in system, holding time, chlorine residual after retention period, date of flushing, and chlorine residual concentration after flushing. Bacteriological analysis shall be done by a state certified testing laboratory for drinking water quality. Disinfecting company shall submit the name of the proposed laboratory as well as the proposed number and location of samples for approval. Approval shall be given by Environmental Health & Safety on each specific job. Notify EH&S, on the Attachment 3: Bacteriological Sampling Notification Form, at least 3 working days prior to the date of sampling. Provide EH&S the Bacteriological Report, indicating date of sampling, sample location, presence or absence of coliform organism (total and fecal coliform), and heterotrophic plate count. A microbial laboratory analysis report is acceptable as Bacteriological Report. C. Preliminary Preparation of the System All fixtures to be served by the potable water system shall be in place at the time of chlorination. Injection Port: provide and install, within 3 feet of the supply main, an injection port for introducing the chlorine solution. An upstream gate valve or other means to control water flow, while connecting chlorination equipment, is required. There shall be no dead-end sections in the system exceeding 3 feet in length. All branches within the system shall lead to an outlet for bleeding and flushing. Prior to injection, it is necessary to place signs on each fixture being treated in order to prevent persons from using heavily chlorinated water. Sign shall read “Heavily chlorinated water — do not use.” D. Chlorination Procedures There are two options available to companies performing the chlorination, the “24 hour hold” method and the “3 hour scrub” method. In general, the “24 hour hold” is the method of choice, but the “3 hour scrub” can be used on small jobs where time is crucial and the chlorinators skills are highly satisfactory. The following is a description of the two procedures: 1. “24 Hour Hold Method” a. The chlorine shall be introduced at such a rate into the supply stream to provide a uniform concentration of chlorine in the entire system. The concentration is to be sufficient to maintain a 25-50 ppm chlorine level at each fixture after a hold period of 24 hours. In order to minimize corrosive effects on the plumbing system, the chlorine residual shall not exceed 150 ppm at any time. b. During injection, the chlorine shall be drawn through each outlet and fixture in the system. In order to expedite the chlorination of hot water systems, it is usually best to drain the water heater prior to beginning the chlorine injection. Then chlorine of proper concentration is found at each outlet, all valves shall be closed, including the service cock and supply valve. In order to prevent tampering with the system during the 24 hour hold period, it is recommended that signs be placed, fixtures be taped, and/or valve handles be removed. c. Testing for the residual concentration in the system at the end of the 24 hours will be done by EH&S. No water shall be released from the system until these samples are taken. A minimum concentration of 10-25 ppm of chlorine must be found at all chosen sampling points. d. After satisfactory compliance with the 10-25 ppm for the 24 hour residual requirement, the system shall be flushed at a relatively high velocity to remove the injected chlorine. Evidence of proper flushing will be reduction of chlorine concentration in the system to no more than 0.5 ppm above that in the normal supply. e. When EH&S has approved the flushing process, the entire system shall be resecured for a holding period of not less than 3 days prior to taking samples for bacteriological analysis. During this holding period, it is again recommended that all valves be closed, taped, and handles removed to maintain chlorination integrity and prevent repetition of the entire process. 2. “3 Hour Scrub Method” a. The chlorine shall be introduced at such a rate into the supply stream to provide a uniform 100 ppm concentration during an entire 3 hour time period with all fixtures flowing. A substantial flow is required at all fixtures; dripping is not acceptable. In order to minimize corrosive effects on the plumbing system, the chlorine residual shall not exceed 150 ppm at any time. b. In order to expedite the chlorination of hot water systems, it is usually best to drain the water heater prior to beginning the chlorine injection. c. Testing for chlorine concentration shall be frequently done by the personnel performing the chlorination and at least once by EH&S. d. After completion of the “3 hour scrub,” the system shall be flushed at a relatively high velocity to remove the injected chlorine. Evidence of proper flushing will be reduction of chlorine concentration in the system to no more than 0.5 ppm above that in the normal supply. e. When EH&S has approved the flushing process, the entire system shall be secured for a holding period of not less than 3 days prior to the taking samples for bacteriological analysis. During this holding period, it is recommended that all valves be closed, taped, and handles removed to maintain chlorination integrity and prevent repetition of the entire process. E. Preliminary Approval and Bacteriological Sampling When EH&S has approved the flushing process, the entire system shall be secured for a holding period of not less than 3 days prior to taking samples for bacteriological analysis. During this holding period, it is recommended that all valves be closed, taped, and handles removed to maintain chlorination integrity and prevent repetition of the entire process. At the completion of the 3 day hold period, bacteriological water samples are taken under the direction of EH&S. The number of necessary samples and sampling locations shall be determined by EH&S. Samples shall be taken from representative locations of the building, particularly drinking water fountains, eyewash stations, etc. A control sample shall also be taken from a building nearby that receives water from the same water main. The domestic water system cannot be used until the effectiveness of the chlorination procedure on the system has been determined by EH&S. If initial bacteriological samples are unsatisfactory, the new building water system should be reflushed and additional samples collected and analyzed. If any of the check samples are also unsatisfactory, the new building water system must be rechlorinated, reflushed, and resampled until satisfactory results are achieved. F. Bacteriological Analysis Water testing must be done by a state certified testing laboratory approved by EH&S. Sample bottles must be provided by the laboratory and analysis must be done in accordance with APHA “Standard Methods.” The laboratory shall report the presence of any E. coli bacteria in a 100 ml sample (this must be negative to be acceptable) and the total plate count of bacteria per ml of the sample (this count must be less than 100 or equal to the supply to be acceptable) G. Final Approval Upon satisfactory completion of all disinfection procedures designated by EH&S and receipt of acceptable bacteriological results, written approval of the system will be provided to the responsible contractor (Attachment 4: Chlorination and Bacteriological Testing Verification and Approval). Failure to fully comply with the above procedures may result in a requirement to repeat chlorination of the system until the specified standards are met.
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Potable (Drinking) Water