Seven days a week, chemists and engineers are hard at work at Seattle’s water quality lab in SoDo. They work to keep us safe, testing H2O from watersheds in the Cascade mountains and throughout the municipal water system.

“There are naturally-occurring things — microorganisms, metals and naturally occurring organic material from leaves, pine needles, etcetera,” said Wylie Harper of Seattle Public Utilities.

The water is treated for those things, but not filtered by man because the Cascade watersheds work as natural filters. The watersheds are off-limits to members of the general public and their man-made pollutants. As for lead contamination, Seattle says that is not an issue.

“We don’t see lead in our source water,” said Harper. “We don’t see it in the watersheds, and we don’t see it coming out of the treatment plants. The typical source of lead is system materials or plumbing materials.”

In other words, lead typically comes from the pipes of older homes and buildings, built before a city-wide ban on lead in 1980. Seattle Public Utilities has procedures in place to make sure those using older lead fixtures stay safe.

“What we do on the supply side and treatment side [is] optimize the chemistry, so it’s as least aggressive or least corrosive as possible on those [older] plumbing materials,” said Harper. “It’s, frankly, it was part of what wasn’t happening in Flint, Michigan. So, a pretty stark contrast there.”

The water chemistry must meet EPA standards and routinely reported to the Washington State Department of Health. A big part of what the experts at the water quality lab do is test samples for lead every part of the way starting at the treatment centers and various points throughout the water system multiple times per week.