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 the operating authority opts to undertake Microbiological sampling, samples shall be considered distribution samples stanndard the meaning of O. Flushing shall continue until the discharged water is free from discoloration, and secondary disinfection has been restored as per 3.

Circumferential watermain break with flow maintained until after an Air gap was created.

The sequence of actions may be varied as appropriate for the specific situation. Notwithstanding the conditions of section 1.

Mechanical removal of Contaminants; Flushing into the excavation; Higher velocity flushing after repairs where practical and feasible. Skip to main content. In developing these procedures, operating authorities may use best management practices that go beyond the minimum requirements in this document.

Watermain breaks with no evident or suspected Contamination are classified as Category 1. Upon completion of the excavation, awa Operator-in-Charge OIC shall conduct a visual inspection to determine the nature of the break. Category 1 watermain breaks are not defined as an observation of improper disinfection in accordance with Section of Schedule 16 of O.

Flushed water may be discharged from a hydrant, plumbing or Appurtenances. Spiral watermain break with evident Contamination.

Watermain disinfection procedure |

The requirements in this section also apply to temporary watermains. Example 3 When using the slug method of chlorination, with a awa 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 at the point of discharge.

Disinfectant residual on final post repair Flushing. The operating authority will attempt to maintain flow from the break, where possible, until an Air gap is established.


Where there is no discharge point to allow for Flushing, the operating authority shall tap the awda on the downstream side of the break and discharge from that point. For relining of existing watermains, the conditions of section 1. The disinfection requirements for new watermains as per Section 1. This procedure also establishes minimum standards for record keeping, and notification to the Ministry and the local Medical Officer of Health.

For planned swabbing and hydraulic e. Chlorine Concentrations and Contact Times for New Watermains At levels over 10 milligrams per litre, a measurement of total chlorine shall be deemed to be equivalent to a measurement of free chlorine. The procedures are required to be followed in order to satisfy conditions imposed by the Director in a drinking water works permit. Notification to the local Ministry office is not required for Category 2 watermain breaks unless:.

The operating authority shall determine if flow can be maintained to the break site until the watermain is excavated.

All samples shall be considered distribution samples, taken and tested in accordance with O. 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. Service pipes of mm diameter and greater shall be considered as watermains for the purposes of this procedure.

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.

The OIC will assess the evidence of Contamination or potential Contamination of awwaa watermain before and during the repair procedure, and shall classify the break into one of two categories as per 3. There is no requirement standxrd undertake Microbiological sampling for Category 1 watermain break repairs. In addition to the requirements described in section 3.

AWWA C / AWWA C / AWWA C – Disinfection Of Water Package

The operating authority shall finalize the plan in agreement with the local Ministry office in consultation with the local Medical Officer of Health. 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 likely to cause an adverse effect, as per Condition 10 of Schedule B of the Municipal Drinking Water Licence.


Watermain repairs involving more than 6 metres of replaced pipe are also classified as Category 2. Staged sampling shall be performed as follows: Examples of watermain breaks that are typical of Category 2 are included below for illustrative purposes only: Chain of custody Date and time of return to normal service Water Advisory declared: If an operating authority believes that contaminated water was directed to users, this will constitute an observation of improper disinfection in accordance with Section of Schedule 16 of O.

Watermain disinfection procedure

The reporting and corrective actions of Schedule 16 and the applicable Schedule 17 or 18 of O. After business hours, the operating authority shall send an e-mail to the e-mail address specified by local Ministry office no later awwq 10 AM the next business day; or in the Special Cases described in sections 3. Longitudinal watermain break with evident Contamination.

The local Ministry office shall be notified as soon as reasonably possible during business hours. This procedure uses a risk management approach to categorize watermain breaks based on the potential for Contamination. 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.

Operating authorities shall develop and document operating procedures for emergency watermain repairs within their systems.

Operating Authorities may choose to provide notification to, or seek advice from, the local Medical Officer of Health at any time.