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Tap water quality report

Los Altos Hills, CA

EPA monitoring detected 11 contaminants across the 1 water supplier serving Los Altos Hills. 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.

1
water supplier
6,245
people served
11
contaminants found
California rankings Lead in California PFAS in California

What was found in Los Altos Hills'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
TTHM
62.686 µg/L 78%
of the EPA limit 80 µg/L
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Chloroform
61.334 µg/L
No EPA limit set
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Total Haloacetic Acids (HAA5)
53.875 µg/L 90%
of the EPA limit 60 µg/L
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Dichloroacetic Acid
30.9 µg/L
No EPA limit set
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Trichloroacetic Acid
24.905 µg/L
No EPA limit set
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Bromodichloromethane
3.905 µg/L
No EPA limit set
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Monochloroacetic Acid
3.59 µg/L
No EPA limit set
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Bromoform
3.22 µg/L
No EPA limit set
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Dibromochloromethane
2.472 µg/L
No EPA limit set
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Dibromoacetic Acid
1.3 µg/L
No EPA limit set
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2019
1/1 SYR4
Lead
0.0060 mg/L 40%
of the EPA limit 0.0150 mg/L
Main supplier: PURISSIMA HILLS WATER DISTRICT · 6,245 people · 2023
1/1 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 Los Altos Hills

SupplierPopulation served
PURISSIMA HILLS WATER DISTRICT 6,245

Frequently asked questions about Los Altos Hills tap water

Is Los Altos Hills tap water safe to drink?

EPA testing detected 11 contaminants in the water serving Los Altos Hills. 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 Los Altos Hills?

1 public water supplier report drinking-water monitoring for Los Altos Hills, California to the EPA. Each is listed above with its population served.

What contaminants are in Los Altos Hills's water?

The contaminants EPA monitoring detected in Los Altos Hills include TTHM, Chloroform, Total Haloacetic Acids (HAA5), Dichloroacetic Acid, Trichloroacetic Acid. 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.