Pipe systems must be correctly operated and maintained in order to deliver good-quality water and to ensure system capacity and reliability.

Operation and maintenance duties may include:

• watermain flushing
• equipment exercising and inspection
• leak detection and repairs
• replacement

Watermain Flushing

Pipe systems can accumulate debris that can cause water quality to deteriorate and allow bacteria to grow.

Watermain flushing is used to discharge debris or contaminants. Flushing moves water at a high flow rate through a pipe network.  In extreme cases, scouring or swabbing, commonly known as pigging, may be required to remove stubborn debris.

Water is flushed in one direction, moving it through the system from one end to another without reintroducing debris-laden water into parts of the system already flushed.

Fire hydrants and blow-offs are used to discharge water from the system during flushing.

*NB: A water system operator should develop a standard operating procedure that includes public notification when flushing.

When to Flush

Flushing should be included in an annual maintenance schedule. More frequent flushing may be required for seasonal issues or unique events such as contamination, breaks, or system repairs.

Avoid flushing during cold weather to prevent ice buildup or freezing of hydrants.

Water Loss and Leak Detection

Water loss may result from one or several of  these factors:

• leaking pipes
• theft
• watermain flushing

Most water loss is due to pipe leaks which can be located through leak detection procedures.

Testing for Leaks

One good method for detecting leaks is hydrostatic testing. This requires isolating a section of pipe and then pressurizing it to ensure that new or repaired work does not leak.

* NB: Leaking pipes can allow contaminants that can cause health problems to enter the water system. This is even more likely if leaking pipes become depressurized.

An example of this is a leaking water pipe that is being drained. Contaminated ground water can be pulled in through a crack and cause the system to be contaminated when it is returned to service.

Pipe Repairs

During pipe repairs, consider possible operational issues and health effects.

For instance, any new pipes and fittings should be disinfected prior to use.