Update: The boil water advisory was lifted on Wednesday Oct. 8 at noon.

As city crews attempt to flush Mercer Island’s water system and find the source of an E. coli contamination, which prompted two  ‘boil water’ advisories within one week, residents are also being asked to do their part.

“People will want to check the website for instructions on home plumbing,” said communications manager Ross Freeman.

The city has been posting updates on its website about the water situation every day since the second boil water advisory was issued on Thursday Oct. 2.

According to Thursday’s press release, the city wants to hear from water customers who have any reason to believe their garden irrigation system is connected without a permitted backflow preventer.

Backflow devices keep sewage from running back into the water system. In supply systems, water is normally maintained at a certain pressure to enable it to flow from the tap, said Bob James of the State Department of Health (DOH). Problems can occur if the pressure drops for some reason, such as a water main burst, frozen pipe or an unexpectedly high demand on the water system.

Without protective assembly devices, the potable water supply can be contaminated by any customer in the system.

Islanders want to help the situation, councilmember Debbie Bertlin said at a special council meeting on Friday Oct. 3.

“What can the community look for?” she asked. “Or is this (search) literally going to happen in the bowels of the system?”

On Sunday, officials started contacting residents who appear to have lapsed backflow inspection records on file, mobilizing certified backflow inspectors to visit homes with potential problems.

All backflow systems must be inspected annually, and registered with the city.

About 25 key properties in close proximity to areas of interests, and without required backflow device inspections on file, were individually contacted. More than 200 second-tier contacts were underway on Monday.

“The City of Mercer Island Utility Department is responsible for protecting you from contaminated water,” according to its website. “Customer responsibilities for the continued success of this program include, obtaining the proper permits for plumbing changes (including new irrigation installation) and receiving inspections of the backflow assembly installation.”

For more information, go to www.mercergov.org/backflow.