Tap WaterIndex

← California

Tap water quality report

Cwsc Los Altos Suburban

EPA monitoring tested this supplier for 112 contaminants and detected 27. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

112
contaminants tested
27
detected
69,973
people served
1
health-based violations
California rankingsLead in CaliforniaPFAS in California
Water source
SWP
Ownership
Private
Counties served
Santa Clara

Compliance record

Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.

1
health-based violations
4
violations on file
0
still open
ViolationTypeStatusPeriod
MCL Health-based Resolved 1992-11-01 → 1992-12-31
MR Monitoring Resolved 2002-01-01 → 2004-12-31
MR Monitoring Resolved 1995-03-29 → 1995-06-07
MR Monitoring Resolved 1995-03-29 → 1995-06-07

PFAS detected

PFAS are industrial “forever chemicals”. These are the EPA's latest nationwide test results (2023–2025).
ContaminantMaxDetection ratePeriod
PFHXS 0.0035 µg/L 2/36 2025

Other contaminants detected

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.
ContaminantLevel vs EPA limitDetection rateSourcePeriod
Nitrate
8929.938 µg/L 89%
of the EPA limit 10000 µg/L
 1308/1310 SYR4 2012–2019
TTHM
70.3 µg/L 88%
of the EPA limit 80 µg/L
 240/275 SYR4 2012–2019
Bromodichloromethane
24.54 µg/L
No EPA limit set
 233/275 SYR4 2012–2019
Dibromochloromethane
28.6 µg/L
No EPA limit set
 233/275 SYR4 2012–2019
Bromoform
20.03 µg/L
No EPA limit set
 226/275 SYR4 2012–2019
Chloroform
30.42 µg/L
No EPA limit set
 220/275 SYR4 2012–2019
Dibromoacetic Acid
13 µg/L
No EPA limit set
 216/263 SYR4 2012–2019
Total Haloacetic Acids (HAA5)
64 µg/L 107%
of the EPA limit, in the worst sample — 60 µg/L
 211/263 SYR4 2012–2019
Dichloroacetic Acid
31 µg/L
No EPA limit set
 186/263 SYR4 2012–2019
Trichloroacetic Acid
18.4 µg/L
No EPA limit set
 173/263 SYR4 2012–2019
Fluoride
210 µg/L 5.3%
of the EPA limit 4000 µg/L
 46/59 SYR4 2012–2019
Barium
200 µg/L 10%
of the EPA limit 2000 µg/L
 34/70 SYR4 2012–2019
Monobromoacetic Acid
2 µg/L
No EPA limit set
 30/263 SYR4 2012–2019
Lead
0.0015 mg/L 10%
of the EPA limit 0.0150 mg/L
 26/26 LCR 2025
Nitrate-Nitrite
7700 µg/L 77%
of the EPA limit 10000 µg/L
 22/22 SYR4 2016–2019
Chromium
10.44 µg/L 10%
of the EPA limit 100 µg/L
 18/99 SYR4 2012–2019
Combined Uranium
2.06216 µg/L 6.9%
of the EPA limit 30 µg/L
 14/59 SYR4 2012–2019
Arsenic
0.5190 µg/L 5.2%
of the EPA limit 10 µg/L
 8/84 SYR4 2012–2019
Copper
4.244 µg/L 0.3%
of the EPA limit 1300 µg/L
 8/103 SYR4 2012–2019
Lead
0.3600 µg/L 2.4%
of the EPA limit 15 µg/L
 8/82 SYR4 2012–2019
Selenium
5.035 µg/L 10%
of the EPA limit 50 µg/L
 8/81 SYR4 2012–2019
Antimony, Total
0.0220 µg/L 0.4%
of the EPA limit 6 µg/L
 7/82 SYR4 2012–2019
Cadmium
0.0140 µg/L 0.3%
of the EPA limit 5 µg/L
 7/83 SYR4 2012–2019
Monochloroacetic Acid
4 µg/L
No EPA limit set
 3/263 SYR4 2012–2019
Beryllium, Total
0.0020 µg/L 0.1%
of the EPA limit 4 µg/L
 1/75 SYR4 2012–2019
Thallium, Total
0.0080 µg/L 0.4%
of the EPA limit 2 µg/L
 1/76 SYR4 2012–2019
85 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,3,7,8-TCDD2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAsbestosAtrazineBhc-GammaBenzeneBenzo(A)PyreneChlorobenzeneCyanideCarbofuranCarbon TetrachlorideChlordaneDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateGross Beta Particle ActivityHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorNetfosaaNfdhaNmefosaaNitriteOxamylPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneLithiumO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
JAMES, SOPHIE
Phone
408-367-8593
Email
sjames@calwater.com

Frequently asked questions about Cwsc Los Altos Suburban

Is Cwsc Los Altos Suburban tap water safe to drink?

EPA monitoring detected 27 contaminants in Cwsc Los Altos Suburban's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.

What contaminants were detected in Cwsc Los Altos Suburban's water?

EPA monitoring detected Nitrate, TTHM, Bromodichloromethane, Dibromochloromethane, Bromoform, and others. The full list with the level and data source for each is above.

How many people does Cwsc Los Altos Suburban serve?

Cwsc Los Altos Suburban reports serving 69,973 people in California, per its EPA record.

Has Cwsc Los Altos Suburban had any water quality violations?

The EPA has 4 violations on file for Cwsc Los Altos Suburban, of which 1 is health-based (a contaminant limit or required treatment was breached) and 0 remain open. The rest are monitoring or reporting failures.

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.