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Tap water quality report

Maple Valley, WA

EPA monitoring detected 17 contaminants across the 5 water suppliers serving Maple Valley. A detection doesn't automatically mean the water is unsafe — see the level at the main supplier for each below, with its EPA source and period.

5
water suppliers
28,874
people served
17
contaminants found
Washington rankings Lead in Washington PFAS in Washington

What was found in Maple Valley's water

The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.

ContaminantLevel vs EPA limitSuppliersSource
Nitrate
1200 µg/L 12%
of the EPA limit 10000 µg/L
Highest in the city: BILLINGTON · 34 people · 2019
3/5 SYR4
Nitrate-Nitrite
1160 µg/L 12%
of the EPA limit 10000 µg/L
Highest in the city: BILLINGTON · 34 people · 2019
2/5 SYR4
Fluoride
600 µg/L 15%
of the EPA limit 4000 µg/L
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2013
1/5 SYR4
Total Haloacetic Acids (HAA5)
48.36 µg/L 81%
of the EPA limit 60 µg/L
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2019
1/5 SYR4
TTHM
42.58 µg/L 53%
of the EPA limit 80 µg/L
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2019
1/5 SYR4
Chloroform
40.62 µg/L
No EPA limit set
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2019
1/5 SYR4
Dichloroacetic Acid
23.84 µg/L
No EPA limit set
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2019
1/5 SYR4
Trichloroacetic Acid
22.47 µg/L
No EPA limit set
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2019
1/5 SYR4
Lead
7 µg/L 47%
of the EPA limit 15 µg/L
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2013
2/5 SYR4
Copper
6 µg/L 0.5%
of the EPA limit 1300 µg/L
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2013
1/5 SYR4
Arsenic
3.38 µg/L 34%
of the EPA limit 10 µg/L
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2013
Highest in the city: 3.685 µg/L — BILLINGTON · 34 people · 2017
3/5 SYR4
Monochloroacetic Acid
3.635 µg/L
No EPA limit set
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2019
1/5 SYR4
Barium
2.95 µg/L 0.1%
of the EPA limit 2000 µg/L
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2013
1/5 SYR4
Bromodichloromethane
2.266 µg/L
No EPA limit set
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2019
1/5 SYR4
Dibromochloromethane
0.8215 µg/L
No EPA limit set
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2019
1/5 SYR4
Pfba
0.0122 µg/L
No EPA limit set
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2024
1/5 UCMR-5
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
Main supplier: CEDAR RIVER WATER & SEWER DISTRICT · 28,671 people · 2025
4/5 LCR
Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of the system's samples — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately. These are the utilities' own EPA-reported results, not a city-wide average. A detection means the lab measured the substance — it isn't the same as exceeding a legal limit. Hover a source tag to see the EPA program and years behind each figure.

Water suppliers serving Maple Valley

SupplierPopulation served
CEDAR RIVER WATER & SEWER DISTRICT 28,671
EDGEHILL WATER ASSN 109
REED RANCH ROAD WATER 36
BILLINGTON 34
165th Ave Water System 24

Frequently asked questions about Maple Valley tap water

Is Maple Valley tap water safe to drink?

EPA testing detected 17 contaminants in the water serving Maple Valley. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.

How many water suppliers serve Maple Valley?

5 public water suppliers report drinking-water monitoring for Maple Valley, Washington to the EPA. Each is listed above with its population served.

What contaminants are in Maple Valley's water?

The contaminants EPA monitoring detected in Maple Valley include Nitrate, Nitrate-Nitrite, Fluoride, Total Haloacetic Acids (HAA5), TTHM. The full list, with the level at the main supplier and the data source, is in the table above.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.