Chlorine Flush FAQs

Frequently Asked Questions are below, but if you don't find what you're looking for, please contact the SSID administrator at or 604-414-8448. If a chlorine flush is in progress, it will be the first entry in the Calendar of Events on the homepage.

What is a chlorine flush?

A chlorine flush is a procedure involving the application of a 12% solution of sodium hypochlorite to one or both of SSID's water tanks in order to disinfect any part of the infrastructure that may have tested positive for E.coli or coliforms.

Is the water safe for drinking?

Yes, the water was declared safe by the Drinking Water Officer of Vancouver Coastal Health, at 9:30AM Saturday September 10, 2022, after a 10-day boil water advisory.

Why is it necessary to kill the coliform bacteria?

SSID is mandated to protect the quality of water that is distributed to residences in the District. Coliforms in increased quantities are associated with an elevated risk of waterborne diseases, including gastroenteritis. Coliforms are living bacteria that divide and multiply, so even a small count should be treated as soon as it is confirmed.

How much bacteria was found in the water?

The August 29 water re-test at Storage Tank 1 showed 4 e.coli of 120 coliforms in 100mL of water. The subsequent water test results at all 8 sample stations from September 7, and all 8 samples from September 20, showed zero e.coli and zero coliforms.

What kind of chlorine is used?

The chlorine used is a sodium hypochlorite 12% solution.

How much chlorine is added to the water?

The amount of chlorine (sodium hypochlorite 12%) is variable. If applying to the 40,000-gallon lower tank, the amount would be 4x more than if applying to the 10,000-gallon upper tank, because the amount of chlorine is based on a prescribed ratio of chlorine to water at its application point, with another calculation for the residual amount to be achieved at the end of the water line. The residual goal is a range of 0.2 parts per million to 2.0 parts per million.

How do I get rid of the smell and taste?

Run your tap for at least 5 minutes. Leave tap water on the counter in an open carafe for a few hours or until the chlorine smell dissipates. Citric acid neutralizes chlorine so a little squeeze of lemon works as well. We have received reports of a chlorine smell still detected in the water after a week. As more people use the water, the smell will dissipate.

How often do you test for E.coli and coliforms?

SSID tests monthly at 8 sample stations throughout the District. All 8 samples must show less than one part per million. The water tests are posted to the Monthly Reports webpage.

Where do the coliforms come from?

At the time of the flush, it may be unknown how bacteria has entered the system. There may be instances where a part of the distribution system is failing, or that organic matter was introduced in above-water openings, or even that bacteria entered during the water sampling procedure itself, regardless of sanitary precautions.

When will SSID do its next chlorine flush?

There is no plan to do another chlorine flush at this time.

Is chlorine the same as bleach?

Both chlorine and bleach come in several forms, so one is not exactly the other. The chlorine used in SSID flushes is a 12% solution of sodium hypochlorite. However, the smell and taste of this disinfectant does smell and taste as you might expect bleach to taste. This does not mean bleach is safe for consumption.

What other chemicals does SSID add to the water?

SSID water is untreated, except when bacteria has been detected. The aquifer water is considered pristine, so does not need treatment. The water does however have natural components, such as minerals for example. Twice per year, SSID does a full spectrum analysis.

What is a typical procedure for a chlorine flush?

Based on the amount of bacteria detected in the water test; the advice of the Drinking Water Officer of Vancouver Coastal Health; and the operator's own knowledge and experience; a preliminary flush with only water might first be conducted to see if that clears the bacteria. If bacteria are still present after a new water test, the operator will do a flush with the sodium hypochlorite 12% solution. The solution is applied to whatever area the operator decides needs to be treated, and is distributed through selected water lines, in a quantity calculated to be both safe for drinking and effective at removing the bacteria.