We read 18 results from City of Arroyo Grande Utilities Division’s 2025 water quality report. No results over a legal limit; 4 above a health goal or guideline.
Serves about 17,963 people · Water system ID CA4010001 · Read the district’s 2025 report (opens in a new tab)
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Results from the 2025 report
Each number is copied from the district’s report and links to the page it’s printed on. Where the report lists several plants, wells or purchased water, the highest is shown.
| Contaminant | Result | Health goal | Legal limit | What it means |
|---|---|---|---|---|
| Arsenicaverage · range ND to 2 · City groundwater · 2025 report | 0.25 ppb | 0.004 ppb | 10 ppb | Above the health goal63x the health goal |
| Copper90th percentile of 30 homes tested, 0 over the action level · Customer taps · 2025 report | 1.1 ppm | 0.3 ppm | 1.3 ppm (action level) | Above the health goal3.7x the health goal |
| Gross alpha (radioactivity)average · range ND to 3.8 · City groundwater · 2025 report | 0.48 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Total dissolved solidsaverage · range 300 to 690 · City groundwater · 2025 report | 543 ppm | — | 500 ppm guideline | Above the guideline1.1x the guideline (taste, odor or stains; not a health limit) |
| Chloramineaverage · range 0.1 to 2.2 · City groundwater · 2025 report | 1.78 ppm | None set | 4 ppm | Below the legal limit |
| Chlorideaverage · range 24 to 110 · City groundwater · 2025 report | 52.8 ppm | — | 250 ppm guideline | Within the guideline |
| Disinfection byproducts (HAA5)average · range 1.9 to 34.6 · Distribution (groundwater area) · 2025 report | 22.9 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)average · range ND to 46.8 · Distribution (groundwater area) · 2025 report | 29.3 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · City groundwater · 2025 report | 0.18 ppm | 1 ppm | 2 ppm | Below the health goal |
| Ironaverage · range ND to 0.95 · printed as 110 ppb · City groundwater · 2025 report | 0.11 ppm | — | 0.3 ppm guideline | Within the guideline |
| Lead90th percentile of 30 homes tested, 0 over the action level · Customer taps · 2025 report | Not detected | 0.2 ppb | 15 ppb (action level) | Not detected |
| Manganeseaverage · range ND to 0.24 · printed as 43.5 ppb · City groundwater · 2025 report | 0.04 ppm | — | 0.05 ppm guideline | Within the guideline |
| Nitrate (as N)average · range ND to 7.9 · City groundwater · 2025 report | 3.99 ppm | 10 ppm | 10 ppm | Below the health goal |
| Seleniumaverage · range ND to 8.1 · City groundwater · 2025 report | 1.01 ppb | 30 ppb | 50 ppb | Below the health goal |
| Sulfateaverage · range 13 to 190 · City groundwater · 2025 report | 133 ppm | — | 250 ppm guideline | Within the guideline |
| Conductivityaverage · range 510 to 1,000 · City groundwater · 2025 report | 836 µS/cm | None set | None | No health limit |
| Hardnessaverage · range 0.46 to 28.1 · City groundwater · 2025 report | 18.7 gpg (320 ppm) | — | — | Very hard |
| Sodiumaverage · range 36 to 110 · City groundwater · 2025 report | 53.4 ppm | None set | None | No health limit |
Utility results describe the whole system, measured where water enters the pipes, not your tap. Your home’s plumbing can add lead or copper.
EPA testing for PFAS and lithium
EPA’s own nationwide testing (UCMR 5) found these in City of Arroyo Grande Utilities Division’s water between Dec 2023 and Sep 2024. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOA5.8 pptFound in 3 of 8 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFOS6.8 pptFound in 3 of 8 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
- PFHxS5.5 pptFound in 4 of 8 samples · highest resultNo federal limit in force for this one
- PFBS11 pptFound in 4 of 8 samples · highest resultNo federal limit in force for this one
- Lithium60 ppbFound in 8 of 8 samples · highest resultAbove EPA’s health reference level of 10 ppb (a guide, not a legal limit)
Source: EPA UCMR 5 occurrence data. The highest single result is shown; one high sample doesn’t mean every glass is that high.
What you can do
Nothing here is an emergency notice: if the district has a violation, it must tell customers directly. If you’d like to lower these at your tap, these are the treatments that remove them, and the catalog shows the models certified for each. Ranking is by certified removal; commissions never change the order.
Copper
Found: Copper
What removes it: Reverse osmosis.
Radium and uranium
Found: Gross alpha (radioactivity)
What removes it: Reverse osmosis.
Salty taste / high TDS
Found: Total dissolved solids
What removes it: Reverse osmosis.
PFAS ("forever chemicals")
Found: PFOA (EPA testing), PFOS (EPA testing)
What removes it: Reverse osmosis.
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