Boil-Water Advisory Lifted for Mercer Island – Read More!

Read Updated Information at – Click News for 8:45 am Full Update

Guidance for Residents Includes Flushing Pipes Before Drinking Water.

(Mercer Island, WA) – The City of Mercer Island announces that the latest test results from water samples collected Saturday have been analyzed and are clear of E Coli. Restaurants may reopen following completion of step-by-step procedures.

All eleven of the samples revealed no presence of E Coli.

One sample did test positive for Total Coliform. An occasional reading for Total Coliform is not uncommon, and does not in itself indicate any health hazard. Most coliform bacteria are a normal part of the environment and they do not cause illness.

“We are gratified to bring this potentially serious incident to an end, and we thank all residents for their sacrifices and food-service establishments for their willingness to cooperate for the health of the community,” said City Manager Noel Treat.

This finding allows the City to lift the Boil-Water Alert in consultation with the Washington State Department of Health. There’s been no increase in gastrointestinal illness seen in local hospitals, and no confirmed cases of E. Coli linked to Mercer Island water.

City crews will continue to inspect system facilities, and monitor the system per normal operating procedure. Water engineers were unable to identify a source of the temporary contamination of the water. All samples taken from the water reservoirs on the Island were clean. On average, boil-water alerts occur a couple times per year in larger water systems across Washington state.

In order to restore the entire water system in the safest manner possible, water consumers are advised to use the following best practices, which include:


  • Flush pipes at home for 5 minutes by running the cold water tap at all faucets until it feels a lot colder; for a residence with multiple levels, start at the top of the house
  • If discolored, run water until it is clear
  • Follow manufacturer’s instructions for appliances such as water filters and water softeners
  • Dispose of all ice from icemakers, make a new batch, and discard that, then wash and sanitize ice trays.

More FAQ information at:


The Mercer Island School District has elected to remain closed on Monday to sanitize its water-related systems. Other private schools may choose to remain open, with precautions, or stay closed. Each school will follow supervised procedures prior to providing water to students. Parents should contact their children’s school for specific re-opening schedules. Public Health – Seattle & King County is providing specific assistance to schools. School administrators should call (206) 263-9566 for guidance.


All restaurants should remain closed until receiving a visit from a public health inspector. A team of inspectors will begin at 9:30am, and all visits are expected to be complete by Noon. After visits from a team of Public Health – Seattle & King County Inspectors, the closure order will be lifted for all 62 permitted food establishments on the Island, including restaurants, coffee shops, and delis. Restaurant owners should call (206) 263-9566. Guidance is available at:

This notice is being issued following consultation with the Washington State Department of Health and Public Health – Seattle & King County.


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