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Tap water quality report

Foster City, CA

EPA monitoring detected 11 contaminants across the 1 water supplier serving Foster City. 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
36,556
people served
11
contaminants found
California rankings Lead in California PFAS in California

What was found in Foster City'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
62.058 µg/L 78%
of the EPA limit 80 µg/L
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Chloroform
59.515 µg/L
No EPA limit set
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Total Haloacetic Acids (HAA5)
43.17 µg/L 72%
of the EPA limit 60 µg/L
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Dichloroacetic Acid
23.94 µg/L
No EPA limit set
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Trichloroacetic Acid
20.9 µg/L
No EPA limit set
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Bromoform
9.17 µg/L
No EPA limit set
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Dibromochloromethane
9.105 µg/L
No EPA limit set
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Bromodichloromethane
8.816 µg/L
No EPA limit set
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Monochloroacetic Acid
3.4 µg/L
No EPA limit set
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Dibromoacetic Acid
1.98 µg/L
No EPA limit set
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2019
1/1 SYR4
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
Main supplier: ESTERO MUNICIPAL IMPROVEMENT DISTRICT · 36,556 people · 2025
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 Foster City

SupplierPopulation served
ESTERO MUNICIPAL IMPROVEMENT DISTRICT 36,556

Frequently asked questions about Foster City tap water

Is Foster City tap water safe to drink?

EPA testing detected 11 contaminants in the water serving Foster City. 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 Foster City?

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

What contaminants are in Foster City's water?

The contaminants EPA monitoring detected in Foster City 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.