What was found in Arroyo Grande'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.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Nitrate-Nitrite | 443490 µg/L 4435% of the EPA limit, at the 95th percentile of samples — 10000 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2018 | 7/13 | SYR4 |
| Nitrate | 7910 µg/L 79% of the EPA limit 10000 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019
Highest in the city: 17400 µg/L — WOODLAND PARK MUTUAL WATER CO · 538 people · 2019 | 11/13 | SYR4 |
| Fluoride | 310 µg/L 7.8% of the EPA limit 4000 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2018
Highest in the city: 790 µg/L — COUNTRY HILLS ESTATES · 60 people · 2019 | 10/13 | SYR4 |
| Barium | 248.5 µg/L 12% of the EPA limit 2000 µg/L Highest in the city: H2O, INC · 70 people · 2017 | 6/13 | SYR4 |
| TTHM | 78.06 µg/L 98% of the EPA limit 80 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019
Highest in the city: 207 µg/L — CANYON CREST MUTUAL BENEFIT WC · 133 people · 2019 | 10/13 | SYR4 |
| Chloroform | 39.96 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019
Highest in the city: 158 µg/L — CANYON CREST MUTUAL BENEFIT WC · 133 people · 2019 | 4/13 | SYR4 |
| Total Haloacetic Acids (HAA5) | 31.56 µg/L 53% of the EPA limit 60 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019
Highest in the city: 115.9 µg/L — CANYON CREST MUTUAL BENEFIT WC · 133 people · 2019 | 4/13 | SYR4 |
| Copper | 92.15 µg/L 7.1% of the EPA limit 1300 µg/L Highest in the city: KEN MAR GARDENS · 84 people · 2017 | 2/13 | SYR4 |
| Dichloroacetic Acid | 18.1 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019
Highest in the city: 69 µg/L — CANYON CREST MUTUAL BENEFIT WC · 133 people · 2019 | 3/13 | SYR4 |
| Lithium | 60 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2024 | 1/13 | UCMR-5 |
| Selenium | 7.675 µg/L 15% of the EPA limit 50 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2018
Highest in the city: 53 µg/L — KEN MAR GARDENS · 84 people · 2017 | 10/13 | SYR4 |
| Trichloroacetic Acid | 9.25 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019
Highest in the city: 40.8 µg/L — CANYON CREST MUTUAL BENEFIT WC · 133 people · 2019 | 3/13 | SYR4 |
| Arsenic | 23.8 µg/L 238% of the EPA limit, at the 95th percentile of samples — 10 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2018
Highest in the city: 40.8 µg/L — COUNTRY HILLS ESTATES · 60 people · 2019 | 6/13 | SYR4 |
| Bromodichloromethane | 22.54 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019
Highest in the city: 36.4 µg/L — CANYON CREST MUTUAL BENEFIT WC · 133 people · 2019 | 5/13 | SYR4 |
| Dibromochloromethane | 18.54 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019 | 8/13 | SYR4 |
| Combined Uranium | 9.20075 µg/L 31% of the EPA limit 30 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2013
Highest in the city: 14.5946 µg/L — VARIAN RANCH MUTUAL WATER · 105 people · 2018 | 5/13 | SYR4 |
| Bromoform | 10.3 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019 | 8/13 | SYR4 |
| Dibromoacetic Acid | 8.285 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019 | 6/13 | SYR4 |
| Lead | 7.4 µg/L 49% of the EPA limit 15 µg/L Highest in the city: RANCHO NIPOMO WATER COMPANY · 44 people · 2017 | 4/13 | SYR4 |
| Monochloroacetic Acid | 3.44 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019
Highest in the city: 5.01 µg/L — CANYON CREST MUTUAL BENEFIT WC · 133 people · 2019 | 2/13 | SYR4 |
| Cadmium | 2 µg/L 40% of the EPA limit 5 µg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2018 | 4/13 | SYR4 |
| Monobromoacetic Acid | 1.495 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2019 | 1/13 | SYR4 |
| Toluene | 0.6200 µg/L 0.1% of the EPA limit 1000 µg/L Highest in the city: RANCHO NIPOMO WATER COMPANY · 44 people · 2017 | 1/13 | SYR4 |
| Lead | 0.0 mg/L 0% of the EPA limit 0.0150 mg/L Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2026
Highest in the city: 0.0170 mg/L — COUNTRY HILLS ESTATES · 60 people · 2025 | 13/13 | LCR |
| PFBS | 0.0110 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2024 | 1/13 | UCMR-5 |
| PFOS | 0.0068 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2024 | 1/13 | UCMR-5 |
| PFOA | 0.0058 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2024 | 1/13 | UCMR-5 |
| PFHXS | 0.0055 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2024 | 1/13 | UCMR-5 |
| Pfpea | 0.0045 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2024 | 1/13 | UCMR-5 |
| Pfhxa | 0.0035 µg/L No EPA limit set Main supplier: CITY OF ARROYO GRANDE UTILITIES DIVISION · 17,963 people · 2024 | 1/13 | UCMR-5 |
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 Arroyo Grande
| Supplier | Population served |
|---|---|
| CITY OF ARROYO GRANDE UTILITIES DIVISION | 17,963 |
| WOODLANDS DEVELOPMENT | 3,862 |
| MESA DUNES MOBILE HOME ESTATES | 600 |
| WOODLAND PARK MUTUAL WATER CO | 538 |
| CANYON CREST MUTUAL BENEFIT WC | 133 |
| EDNA VALLEY RANCH EAST | 132 |
| VARIAN RANCH MUTUAL WATER | 105 |
| KEN MAR GARDENS | 84 |
| LAGUNA NEGRA MUTUAL WATER CO. | 80 |
| H2O, INC | 70 |
| COUNTRY HILLS ESTATES | 60 |
| RANCHO NIPOMO WATER COMPANY | 44 |
| TERRA DE ORO WATER COMPANY | 38 |
Frequently asked questions about Arroyo Grande tap water
Is Arroyo Grande tap water safe to drink?
EPA testing detected 30 contaminants in the water serving Arroyo Grande. 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 Arroyo Grande?
13 public water suppliers report drinking-water monitoring for Arroyo Grande, California to the EPA. Each is listed above with its population served.
What contaminants are in Arroyo Grande's water?
The contaminants EPA monitoring detected in Arroyo Grande include Nitrate-Nitrite, Nitrate, Fluoride, Barium, TTHM. 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.