Is Altadena, CA Tap Water Safe? Quality & Contaminants

What was found in Altadena's water

The highest level seen across the city's suppliers, the EPA limit for each, and where the figure comes from.

Contaminant	Level vs EPA limit	Suppliers	Source
Nitrate-Nitrite	900000 µg/L 9000% of the EPA limit, in the worst sample — 10000 µg/L	2/3	SYR4
Nitrate	11000 µg/L 110% of the EPA limit, in the worst sample — 10000 µg/L	3/3	SYR4
Fluoride	3500 µg/L 88% of the EPA limit 4000 µg/L	3/3	SYR4
Total Haloacetic Acids (HAA5)	136 µg/L 227% of the EPA limit, in the worst sample — 60 µg/L	3/3	SYR4
TTHM	103.8 µg/L 130% of the EPA limit, in the worst sample — 80 µg/L	3/3	SYR4
Chloroform	88.2 µg/L No EPA limit set	3/3	SYR4
Trichloroacetic Acid	83.2 µg/L No EPA limit set	3/3	SYR4
Copper	73 µg/L 5.6% of the EPA limit 1300 µg/L	1/3	SYR4
Lithium	53.6 µg/L No EPA limit set	1/3	UCMR-5
Dichloroacetic Acid	50.6 µg/L No EPA limit set	3/3	SYR4
Combined Uranium	37.25 µg/L 124% of the EPA limit, in the worst sample — 30 µg/L	3/3	SYR4
Bromodichloromethane	27.1 µg/L No EPA limit set	3/3	SYR4
Dibromochloromethane	17.6 µg/L No EPA limit set	3/3	SYR4
Carbon Tetrachloride	5.8 µg/L 116% of the EPA limit, in the worst sample — 5 µg/L	1/3	SYR4
Bromoform	5.6 µg/L No EPA limit set	3/3	SYR4
Dibromoacetic Acid	5.6 µg/L No EPA limit set	3/3	SYR4
Arsenic	4.8 µg/L 48% of the EPA limit 10 µg/L	2/3	SYR4
Tetrachloroethylene	4.8 µg/L 96% of the EPA limit 5 µg/L	3/3	SYR4
Monochloroacetic Acid	3.4 µg/L No EPA limit set	1/3	SYR4
Trichloroethylene	2.6 µg/L 52% of the EPA limit 5 µg/L	1/3	SYR4
PFOS	0.0190 µg/L No EPA limit set	1/3	UCMR-5
PFHXS	0.0110 µg/L No EPA limit set	1/3	UCMR-5
PFOA	0.0085 µg/L No EPA limit set	1/3	UCMR-5
Pfba	0.0057 µg/L No EPA limit set	1/3	UCMR-5
PFBS	0.0035 µg/L No EPA limit set	1/3	UCMR-5
Pfpea	0.0035 µg/L No EPA limit set	1/3	UCMR-5
Pfhxa	0.0031 µg/L No EPA limit set	1/3	UCMR-5
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L	3/3	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 single worst sample on record — 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 Altadena

Supplier	Population served
LINCOLN AVENUE WATER CO.	16,088
RUBIO CANON LAND & WATER ASSOCIATION	9,215
LAS FLORES WATER CO.	4,847

Frequently asked questions about Altadena tap water

Is Altadena tap water safe to drink?

EPA testing detected 28 contaminants in the water serving Altadena. 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 Altadena?

3 public water suppliers report drinking-water monitoring for Altadena, California to the EPA. Each is listed above with its population served.

What contaminants are in Altadena's water?

The contaminants EPA monitoring detected in Altadena include Nitrate-Nitrite, Nitrate, Fluoride, Total Haloacetic Acids (HAA5), TTHM. The full list, with the highest level found 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.