Water supply is clean, robust, but losses betray aging infrastructure

The City of Mercer Island’s 2013 Annual Water Quality report arrived last week in Island mailboxes. The report is prepared each year in conjunction with Seattle Public Utilities. In it, the two agencies detail the present state of the regional water supply.

Mercer Island gets its water from the enormous Cedar River Watershed, owned by Seattle Public Utilities, that supplies water to 1.4 million people in central Puget Sound.

Data collected each year shows that the water meets or exceeds standards for safe drinking water. Yet while there is plenty of clean water available in the region now, it remains a finite and critical resource.

In 2013, the city purchased 750.9 million gallons through the City of Seattle. However, city records only account for 67.6 million gallons. That means more than 9 percent of the water delivered to the Island was lost to leaks and breaks, faulty meters or unauthorized (stolen) water usage. These losses are termed “unaccounted for water” or “non-revenue water.” As such, Mercer Island buys water that its citizens do not use.

A loss of 9.2 percent is not unusual, experts say. A check of websites that govern U.S. domestic water systems indicate that losses at ten percent or less is generally seen as “acceptable.”

The loss of revenue is passed on to customers through rates.

Glenn Boettcher, the Maintenance Director for the city, said, “We do our best to keep our system loss as low as possible.”

“We routinely search for leaks, even quite small ones, and any we find are repaired right away,” he continued. “When we compare ourselves to other water utilities in our region, our system loss is about average.It’s one of the challenges of having an aging water system.”

Beyond summarizing the quality and logistics of the water supply, the report reminds Islanders how to conserve and protect water resources and save money as well.

Mercer Island is a member of the Saving Water Partnership that is made up of 18 regional water utilities. The Partnership has set a six-year goal to reduce water consumption despite expected population growth.

The U.S. Geological Survey’s Water Science School estimates each person in the U.S. uses about 80-100 gallons of water per day. The USGS says the largest amount of water used by households is in the bathroom.

Despite leaks and the expected increase of domestic water use, Seattle Public Utilities have forecast that there will be sufficient water resources for the future. Yet if there is an earthquake or emergency, water from SPU may not be deliverable to the Island.

In order to have water on hand for residents in the event of an earthquake or emergency, the city built an emergency well at Rotary Park near the library. The joint city and SPU report reminds residents that the emergency well is not designed to supply water through the existing pipes of the city’s distribution system. Residents will be able to get water on a walk-up basis or from a water truck.


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