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Tap water quality report

Clearlake, CA

EPA monitoring detected 20 contaminants across the 3 water suppliers serving Clearlake. A detection doesn't automatically mean the water is unsafe — see the highest level found for each below, with its EPA source and period.

3
water suppliers
13,725
people served
20
contaminants found
California rankings Lead in California PFAS in California

What was found in Clearlake's water

The highest level seen across the city's suppliers, the EPA limit for each, and where the figure comes from.

ContaminantLevel vs EPA limitSuppliersSource
Nitrate
800 µg/L 8%
of the EPA limit 10000 µg/L
 2/3 SYR4
Fluoride
280 µg/L 7%
of the EPA limit 4000 µg/L
 3/3 SYR4
Barium
140 µg/L 7%
of the EPA limit 2000 µg/L
 2/3 SYR4
TTHM
116.55 µg/L 146%
of the EPA limit, in the worst sample — 80 µg/L
 3/3 SYR4
Chloroform
94.23 µg/L
No EPA limit set
 2/3 SYR4
Total Haloacetic Acids (HAA5)
76.9 µg/L 128%
of the EPA limit, in the worst sample — 60 µg/L
 2/3 SYR4
Dichloroacetic Acid
52.6 µg/L
No EPA limit set
 2/3 SYR4
Bromate
37 µg/L 370%
of the EPA limit, in the worst sample — 10 µg/L
 2/3 SYR4
Lithium
25 µg/L
No EPA limit set
 2/3 UCMR-5
Trichloroacetic Acid
21 µg/L
No EPA limit set
 2/3 SYR4
Bromodichloromethane
18.52 µg/L
No EPA limit set
 3/3 SYR4
Monochloroacetic Acid
10.3 µg/L
No EPA limit set
 2/3 SYR4
Dibromochloromethane
7.17 µg/L
No EPA limit set
 3/3 SYR4
Arsenic
6.5 µg/L 65%
of the EPA limit 10 µg/L
 2/3 SYR4
Dibromoacetic Acid
4.1 µg/L
No EPA limit set
 2/3 SYR4
Bromoform
3.14 µg/L
No EPA limit set
 3/3 SYR4
Monobromoacetic Acid
1.3 µg/L
No EPA limit set
 1/3 SYR4
Pfba
0.0082 µg/L
No EPA limit set
 1/3 UCMR-5
Lead
0.0046 mg/L 31%
of the EPA limit 0.0150 mg/L
 3/3 LCR
Pfpea
0.0039 µg/L
No EPA limit set
 1/3 UCMR-5
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 single worst sample on record — 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 Clearlake

SupplierPopulation served
HIGHLANDS MUTUAL WATER COMPANY 7,772
KONOCTI COUNTY WATER DISTRICT 5,928
WINDFLOWER POINT MUTUAL WATER COMPANY 25

Frequently asked questions about Clearlake tap water

Is Clearlake tap water safe to drink?

EPA testing detected 20 contaminants in the water serving Clearlake. 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 Clearlake?

3 public water suppliers report drinking-water monitoring for Clearlake, California to the EPA. Each is listed above with its population served.

What contaminants are in Clearlake's water?

The contaminants EPA monitoring detected in Clearlake include Nitrate, Fluoride, Barium, TTHM, Chloroform. The full list, with the highest level found 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.