Drinking water quality · 2024
· Verified
What's in Seattle, WA tap water
13 contaminants were measured in the Seattle, WA water system's 2024 annual report. Each is shown below against its federal limit.
- Reporting year
- 2024
- Contaminants measured
- 13
- Over federal limit
- 0
- Approaching the limit
- 0
- Service area
- WA
Disinfection byproducts
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| HAA5Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. | 33 ug/LAverageSystem-wide | 60 ug/LMCL | Within the limit |
| TTHMTotal trihalomethanes — a group of four chemicals (including chloroform) formed when chlorine reacts with natural organic matter. | 43 ug/LAverageSystem-wide | 80 ug/LMCL | Within the limit |
| BromateA disinfection byproduct formed when bromide-containing water is treated with ozone. | 0.3 ug/LAverageSystem-wide | 0 ug/LMCLG | Detected — no federal limit |
Disinfectants
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChlorineA disinfectant added to drinking water to kill bacteria and viruses. | 1 mg/LAverageSystem-wide | 4 mg/LMRDLG | Within the limit |
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| FluorideA mineral often added to drinking water to help prevent tooth decay. | 0.7 mg/LAverageSystem-wide | 4 mg/LMCLG | Within the limit |
| NitrateA compound from fertilizer runoff, septic systems, and erosion of natural deposits. | 0.08 mg/LAverageSystem-wide | 10 mg/LMCLG | Within the limit |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| CopperA metal that enters water from corroding household plumbing. | 0.12 mg/L90th percentileAt the tap | 1.3 mg/LMCLG | Within the limit |
| BariumA metal from erosion of natural deposits and industrial discharge. | 1.2 ug/LAverageSystem-wide | 2000 ug/LMCLG | Within the limit |
| ArsenicA naturally occurring element that also enters water from industry and agriculture. | 0.23 ug/LAverageSystem-wide | 0 ug/LMCLG | Detected — no federal limit |
| LeadA toxic metal that leaches into water from old service lines, solder, and plumbing fixtures. | 2.8 ug/L90th percentileAt the tap | 0 ug/LMCLG | Detected — no federal limit |
Microbial
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Total ColiformA group of bacteria used as an indicator of overall water-system sanitation. | 0.6 %AverageSystem-wide | 0 %MCLG | Detected — no federal limit |
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TOCTotal organic carbon — a measure of organic material dissolved in the water. | 1.24 mg/LAverageSystem-wide | None set | Detected — no federal limit |
| TurbidityA measure of cloudiness from suspended particles in the water. | 0.04 NTUAverageSystem-wide | None set | Detected — no federal limit |
People also ask about Seattle, WA's water
+Is Seattle, WA tap water safe to drink in 2024?
Every one of the 13 contaminants measured in Seattle, WA's 2024 Consumer Confidence Report is below its federal limit. "Safe" under the EPA's drinking-water standards is health-based, not aesthetic — but by those standards, no measured contaminant in this report exceeds its enforceable threshold. Individual health concerns (e.g. immunocompromised, infant, pregnancy) may warrant additional filtering regardless of compliance.
+What contaminants are in Seattle, WA tap water?
13 contaminants were measured in Seattle, WA's 2024 Consumer Confidence Report, spanning metals, disinfection byproducts, and inorganic chemicals. 11 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Where does the data on this page come from?
Every value is transcribed from Seattle, WA's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is Seattle, WA's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2024 report; a new report will replace it once the utility publishes its next annual update.