Loss of / Negative Water Pressure

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Some water systems that serve a municipality cannot maintain water pressure following an extended power failure.  Larger systems typically have dedicated stand-by power or an elevated storage tank to maintain pressure.  Locations that do not have stand–by power capability should:

During a power failure, the water system will lose pressure over time and there is a risk that contaminated water could flow into the system. Therefore, in the event of a power failure:

Ø      Minimize the use of water (this will help to prevent loss of pressure)

If there is a significant loss of pressure:

Ø      Assume the water may not be safe to drink, use an alternative supply of drinking water or bring your drinking water to a rapid, rolling boil for one minute before use.

Following a power failure with no significant loss of pressure, it is safe to immediately resume all uses of the water system.

Following a power failure or a main break with a significant loss of pressure, the water pressure will be restored. The Operating Authority will be testing the water for possible bacterial contamination and ensuring that adequate levels of disinfection are present throughout the water system. However, it is recommended you take the following precautions in your home:

Ø      Run the water until it feels noticeably cool. Then run for another minute (this will flush the plumbing in your home).

Ø      Remove, rinse and replace any screen on the tap.

Ø      For the first 3 days following the return of water pressure, assume the water may not be safe to drink, use an alternative supply of drinking water or bring your drinking water to a rapid, rolling boil for one minute before use. This precaution applies to water for drinking, cooking and oral hygiene.

Ø      Other household uses of water such as cleaning, clothes washing, dishwashing and bathing can commence immediately after the return of water pressure.

Ø      After 3 days you can assume the water is safe for all uses unless the Health Unit has advised you otherwise. (Testing for bacterial contamination takes 2 days. Up to another day is required for sampling and transport of the samples to the laboratory.)

Ø      If you have a water softener, or other water treatment attached to the cold water supply line, you should consider additional flushing. Ask your supplier for appropriate directions.

This fact sheet has been provided through the co-operative efforts of the Grey Bruce Health Unit, Ministry of Environment and Ontario Clean Water Agency.

For more information contact:

Grey Bruce Health Unit at 519-376-93420

Rev. July 17, 2006