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
| Violation | Type | Status | Period |
|---|---|---|---|
| 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).
| Contaminant | Max | Detection rate | Period |
|---|---|---|---|
| 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 95th percentile of this
system's samples — over 100% is worth reading, but is not by itself a
violation. Where a single sample came in higher than that percentile, it
is noted under the bar. Formal violations are listed separately.
| Contaminant | Level vs EPA limit | Detection rate | Source | Period |
|---|---|---|---|---|
| Nitrate | 8440.56 µg/L 84% of the EPA limit 10000 µg/L
worst single sample: 8929.94 µg/L | 1308/1310 | SYR4 | 2012–2019 |
| TTHM | 60.51 µg/L 76% of the EPA limit 80 µg/L
worst single sample: 70.3 µg/L | 240/275 | SYR4 | 2012–2019 |
| Bromodichloromethane | 19.558 µg/L No EPA limit set
worst single sample: 24.54 µg/L | 233/275 | SYR4 | 2012–2019 |
| Dibromochloromethane | 25 µg/L No EPA limit set
worst single sample: 28.6 µg/L | 233/275 | SYR4 | 2012–2019 |
| Bromoform | 15.95 µg/L No EPA limit set
worst single sample: 20.03 µg/L | 226/275 | SYR4 | 2012–2019 |
| Chloroform | 16.065 µg/L No EPA limit set
worst single sample: 30.42 µg/L | 220/275 | SYR4 | 2012–2019 |
| Dibromoacetic Acid | 11 µg/L No EPA limit set
worst single sample: 13 µg/L | 216/263 | SYR4 | 2012–2019 |
| Total Haloacetic Acids (HAA5) | 29.25 µg/L 49% of the EPA limit 60 µg/L
worst single sample: 64 µg/L | 211/263 | SYR4 | 2012–2019 |
| Dichloroacetic Acid | 12 µg/L No EPA limit set
worst single sample: 31 µg/L | 186/263 | SYR4 | 2012–2019 |
| Trichloroacetic Acid | 11 µg/L No EPA limit set
worst single sample: 18.4 µg/L | 173/263 | SYR4 | 2012–2019 |
| Fluoride | 207.5 µg/L 5.2% of the EPA limit 4000 µg/L
worst single sample: 210 µg/L | 46/59 | SYR4 | 2012–2019 |
| Barium | 183.922 µg/L 9.2% of the EPA limit 2000 µg/L
worst single sample: 200 µg/L | 34/70 | SYR4 | 2012–2019 |
| Monobromoacetic Acid | 1.565 µg/L No EPA limit set
worst single sample: 2 µg/L | 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 | 7100 µg/L 71% of the EPA limit 10000 µg/L
worst single sample: 7700 µg/L | 22/22 | SYR4 | 2016–2019 |
| Chromium | 10.3524 µg/L 10% of the EPA limit 100 µg/L
worst single sample: 10.44 µg/L | 18/99 | SYR4 | 2012–2019 |
| Combined Uranium | 1.98081 µg/L 6.6% of the EPA limit 30 µg/L
worst single sample: 2.06216 µg/L | 14/59 | SYR4 | 2012–2019 |
| Arsenic | 0.5176 µg/L 5.2% of the EPA limit 10 µg/L
worst single sample: 0.5190 µg/L | 8/84 | SYR4 | 2012–2019 |
| Copper | 3.7414 µg/L 0.3% of the EPA limit 1300 µg/L
worst single sample: 4.244 µg/L | 8/103 | SYR4 | 2012–2019 |
| Lead | 0.3208 µg/L 2.1% of the EPA limit 15 µg/L
worst single sample: 0.3600 µg/L | 8/82 | SYR4 | 2012–2019 |
| Selenium | 3.92725 µg/L 7.9% of the EPA limit 50 µg/L
worst single sample: 5.035 µg/L | 8/81 | SYR4 | 2012–2019 |
| Antimony, Total | 0.0181 µg/L 0.3% of the EPA limit 6 µg/L
worst single sample: 0.0220 µg/L | 7/82 | SYR4 | 2012–2019 |
| Cadmium | 0.0125 µg/L 0.3% of the EPA limit 5 µg/L
worst single sample: 0.0140 µg/L | 7/83 | SYR4 | 2012–2019 |
| Monochloroacetic Acid | 3.82 µg/L No EPA limit set
worst single sample: 4 µg/L | 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
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.