Is Twain Harte Community Services District Tap Water Safe? Quality Report

Water source: Surface water
Ownership: Local government
Counties served: Tuolumne

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.

health-based violations

violations on file

still open

Violation	Type	Status	Period
TT	Health-based	Resolved	2004-07-01 → 2004-09-30
TT	Health-based	Resolved	2004-07-01 → 2004-09-30
TT	Health-based	Resolved	1995-03-01 → 1995-03-31
TT	Health-based	Resolved	1995-03-01 → 1995-03-31
MON	Monitoring	Resolved	2025-04-01 → 2025-05-31
MON	Monitoring	Resolved	2025-04-01 → 2025-05-31
Other	Monitoring	Archived	1980-07-28 → 1980-08-27

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
Chloroform	72.62 µg/L No EPA limit set worst single sample: 79.9 µg/L	49/51	SYR4	2013–2019
TTHM	74.78 µg/L 93% of the EPA limit 80 µg/L worst single sample: 81.5 µg/L	49/51	SYR4	2013–2019
Total Haloacetic Acids (HAA5)	46.82 µg/L 78% of the EPA limit 60 µg/L worst single sample: 49 µg/L	49/49	SYR4	2013–2019
Dichloroacetic Acid	17.875 µg/L No EPA limit set worst single sample: 20.4 µg/L	48/49	SYR4	2013–2019
Trichloroacetic Acid	27.765 µg/L No EPA limit set worst single sample: 31.7 µg/L	48/49	SYR4	2013–2019
Bromodichloromethane	1.95 µg/L No EPA limit set worst single sample: 2.33 µg/L	43/51	SYR4	2013–2019
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L	23/23	LCR	2024
Nitrate	900 µg/L 9% of the EPA limit 10000 µg/L	16/44	SYR4	2012–2019
Monochloroacetic Acid	7.5305 µg/L No EPA limit set worst single sample: 11 µg/L	10/49	SYR4	2013–2019
Combined Uranium	17.0218 µg/L 57% of the EPA limit 30 µg/L worst single sample: 18.476 µg/L	9/9	SYR4	2015–2019
Nitrate-Nitrite	981.45 µg/L 9.8% of the EPA limit 10000 µg/L worst single sample: 1050 µg/L	4/10	SYR4	2012–2017
Toluene	3.189 µg/L 0.3% of the EPA limit 1000 µg/L worst single sample: 3.36 µg/L	4/15	SYR4	2013–2019
Barium	86.12 µg/L 4.3% of the EPA limit 2000 µg/L worst single sample: 89.5 µg/L	3/13	SYR4	2012–2019
Dichloromethane	2.094 µg/L 42% of the EPA limit 5 µg/L worst single sample: 2.12 µg/L	3/15	SYR4	2013–2019
Fluoride	697.9 µg/L 17% of the EPA limit 4000 µg/L worst single sample: 742 µg/L	3/13	SYR4	2012–2019
Dibromochloromethane	1.32815 µg/L No EPA limit set worst single sample: 1.37 µg/L	2/51	SYR4	2013–2019
Monobromoacetic Acid	13.5435 µg/L No EPA limit set worst single sample: 14.2 µg/L	2/49	SYR4	2013–2019
Arsenic	2.3 µg/L 23% of the EPA limit 10 µg/L	1/14	SYR4	2012–2019
Beryllium, Total	3.3 µg/L 83% of the EPA limit 4 µg/L	1/13	SYR4	2012–2019
Cadmium	2.8 µg/L 56% of the EPA limit 5 µg/L	1/13	SYR4	2012–2019
Chromium	11.1 µg/L 11% of the EPA limit 100 µg/L	1/13	SYR4	2012–2019
Combined Radium (-226 And -228)	0.3940 pCi/L 7.9% of the EPA limit 5 pCi/L	1/1	SYR4	2019
Dibromoacetic Acid	2.93 µg/L No EPA limit set	1/49	SYR4	2013–2019
Nitrite	0.2740 µg/L 0% of the EPA limit 1000 µg/L	1/13	SYR4	2012–2019

35 contaminants tested, none detected

1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-DichloropropaneAntimony, TotalAsbestosAtrazineBenzeneBenzo(A)PyreneBromoformChlorobenzeneCopperCarbon TetrachlorideDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateEthylene DibromideEthylbenzeneLassoLeadMercurySeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact: TROTT, TOM
Phone: 209-586-2172
Email: ttrott@twainhartecsd.com

Frequently asked questions about Twain Harte Community Services District

Is Twain Harte Community Services District tap water safe to drink?

EPA monitoring detected 24 contaminants in Twain Harte Community Services District'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 Twain Harte Community Services District's water?

EPA monitoring detected Chloroform, TTHM, Total Haloacetic Acids (HAA5), Dichloroacetic Acid, Trichloroacetic Acid, and others. The full list with the level and data source for each is above.

How many people does Twain Harte Community Services District serve?

Twain Harte Community Services District reports serving 2,378 people in California, per its EPA record.

Has Twain Harte Community Services District had any water quality violations?

The EPA has 7 violations on file for Twain Harte Community Services District, of which 4 are 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.