AWWA C Disinfecting Water Mains. Current; Document Language: English; Published By: American Water Works Association (AWWA). This standard presents essential procedures for the disinfection of new and repaired potable water mains. All new water mains shall be disinfected before they. FIELD CHLORINATION. • AWWA/ANSI C – Disinfecting Water Mains. • First standard approved Sept. 30, • Latest revision June 1.

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Where copper pipe is used for smaller diameter watermains, Table 1 does not apply.

When using the slug method of chlorination, with a minimum contact time of 3 hours, the chlorine concentration shall be measured in the slug at the beginning of the disinfection process, as the slug moves through the watermain, and stqndard the point of discharge. Refer to Appendices A and B for awwwa flowchart and pictures to better understand the criteria to determine the categories of awea breaks. Return to normal service is contingent upon the corrective actions and sampling plan being completed to the satisfaction of the local Ministry office in consultation with the local Medical Officer of Health.

Examples of typical steps for Category 1, 2 and for special cases are attached as Appendices C, D and E respectively. Skip to main content. Discharges of flushed water are also regulated under Condition 4. Follow the steps stqndard in section 3. For new watermains with limited sampling points available, an alternative method of collecting Microbiological samples is called staged sampling.

Service pipes of mm diameter and greater shall be considered as watermains for the purposes of this procedure. If the water level in the excavation rises such that the Air gap is not maintained after flow from the break has been discontinued, then the watermain break shall be classified as Category 2.

Watermain disinfection procedure |

If planned maintenance, indicate type of planned maintenance e. The operating authority shall record the duration of disinfection, as well as stanfard initial dose and remaining residual at the end of the contact time. Return to normal service is contingent upon the corrective actions and sampling plan being completed to the satisfaction of the local Ministry office in consultation with local Medical Officer of Health.


If Contamination awaa evident or suspected, the procedures defined under section 3 for Category 2 watermain breaks shall apply. The operating authority shall implement the plan as prescribed and the watermain cannot be put back in service until the cleaning, disinfection and sampling is completed as per the plan unless a Water Advisory is declared.

Flushing shall continue until the discharged water is free from discoloration, and secondary disinfection has been restored as per 3. If there is evident or suspected chemical Contamination of a watermain, in addition to the procedures in sections 3. Added, modified, replaced, extended; or Stsndard out of service for standarc, repair or other activities that may lead to Contamination, shall be disinfected before being put into service in accordance with the provisions of the AWWA C — Standard for Disinfecting Awwwa Mains or an equivalent procedure.

For all other types of cleaning e. The sampling will typically occur at the point of Flushing, and may take place from sampling ports, hydrants, blow-offs, or premise plumbing. Flushing watermain cleaning, the requirements of section 3.

Staged sampling shall be performed as follows:. Circumferential watermain break with flow maintained until after an Air gap was created. This procedure uses a risk management approach to categorize watermain breaks based on the potential for Contamination.

The following flowchart depicts the requirements for special case Contamination sewage or chemical as a result of a watermain break. Dechlorination of discharged water is required for any water that is directed into surface water or if the discharge into the natural environment causes or is c65 to cause an adverse effect, as per Condition 10 of Schedule Atandard of the Municipal Drinking Water Licence.

Additional steps shall be undertaken as appropriate to remove Contaminants from the watermain, such as:. After business hours, the operating authority shall send an e-mail to the e-mail address specified by local Ministry office no later than 10 AM the next business day; or in the Special Cases described in sections 3.


Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes only:.

Tags Environment and energyDrinking water. Flow may be discontinued after an Air gap has been created. Category 1 watermain breaks are not defined as an observation of improper disinfection in accordance with Section of Schedule 16 of O.

If chlorine disinfection was used, indicate initial concentration, contact time, final concentration and final concentration as percentage of initial concentration.

Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes only: When performing maintenance and repair activities as per sections 1.

Spiral watermain break with evident Contamination. Disinfectant residual on final post repair Flushing. If these disinfectant concentrations cannot be achieved, Flushing shall continue until the disinfectant concentration at the point of Flushing is representative of the system sandard in the break area, determined by sampling upstream of the break area and downstream at the Flushing location, or by using documented benchmarks for the area, as long as free chlorine concentrations are at least 0.

This definition does not include recharging the watermain or a requirement to achieve scouring velocity within the watermain.

Watermain disinfection procedure

If final disinfectant residual is less than 0. Operating authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time. There is no requirement to undertake Microbiological sampling for Category 1 watermain break repairs. In addition to the procedures in 3. The affected watermain s may not be put back in service before the corrective actions and sampling plan are completed unless a Water Advisory is declared.

The requirements in this section also apply to temporary watermains. The operating authority shall determine if flow can be maintained to the break site until the watermain is excavated.