Bacteria in water supply prompts notice

A Boil water alert was issued for the Tigard area Wednesday.

Effective immediately, the Tigard Water Service Area advised customers to boil their water before consuming it in thee following locations:

• Durham

• King City

• Bull Mountain, including unincorporated areas of Washington County

• Two-thirds of Tigard

Two routine water samples, collected on Monday, Nov. 19, showed possible bacterial contamination. Follow-up samples were collected on Tuesday, Nov. 20, as soon as city staff was aware of the initial sample results.

The follow-up samples also tested positive, prompting the boil water notice. The positive tests indicate the drinking water may be contaminated with human or animal wastes.

"Within the service area, tap water used for drinking, food preparation, brushing teeth, washing dishes and making ice should be heated to a full rolling boil for at least one minute. Boiling the water will kill the bacteria identified in the samples. Any consumables – such as ice or beverages – made with tap water after Sunday, November 18 should be discarded," the notice says.

The bacteria found were total coliforms and E. coli. Although the specific strain of E. coli is not known, the strains associated with serious illness are rarely found in water supplies.

It is not known how the bacteria entered the water supply.

In response to the contamination, crews began flushing the water distribution system on Wednesday, Nov. 21. Following flushing, the water will be sampled again.

Results from those samples will be available Thursday morning and will determine whether the boil water notice can be lifted. Customers will be notified when they no longer need to boil their water.

For more information, including possible health effects, visit visit

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