Seattle, WA tap water quality

Is there PFAS in Seattle's water?

No PFAS were detected in Seattle's water during EPA's UCMR 5 monitoring. That programme tests for 29 individual PFAS compounds at reporting limits in the low parts-per-trillion, so a non-detect here is a meaningful result rather than an absence of testing.

How much lead is in Seattle's tap water?

Seattle's most recent lead 90th-percentile result is 1.6 ppb. That means nine in ten sampled homes measured at or below that level, and it is a summary figure, not the maximum any single household saw. The federal action level is 15 ppb, but that is a trigger for utility action, not a health threshold: no level of lead exposure is considered safe (EPA, CDC), and lead almost always enters through household plumbing and service lines rather than the treatment plant.

Is Seattle tap water safe to drink?

Seattle's water meets federal legal standards on the measures its utility reports. We score it 98 out of 100 against health-based guidance, which is stricter than the legal minimum by design. Those are two different questions, and most coverage collapses them: a supply can be entirely lawful and still carry readings above the level health researchers would prefer. This score answers the second question, and the table above shows exactly which measure moved it.

Has Seattle's water been in violation?

EPA's compliance record shows 29 violations for this system, 4 of them health-based, none of them since 2020. A health-based violation means a contaminant exceeded a legal limit or required treatment was not delivered. The rules most often cited here: Surface Water Treatment Rule (2), Lead and Copper Rule (2). Most recent entry: 2015.

Context matters when reading these. Large systems accumulate more violations simply by having more sampling points and more years on record, and a violation from a decade ago says little about water leaving the plant today. What is worth attention is a recent pattern rather than a single old entry.

What can you do about it?

If lead is the concern here, the fix is almost never the treatment plant: it's the service line and the plumbing inside the building. Running the tap for thirty seconds after long stagnation, using cold water for drinking and cooking, and asking your utility whether your address has a lead service line are all free. A filter certified to NSF/ANSI 53 for lead is the next step. If PFAS is the concern, NSF/ANSI 53 does not cover it: look for NSF/ANSI 58 reverse osmosis or a filter specifically certified under NSF/ANSI 53 for PFOA and PFOS reduction.