Water quality · CA
California Water Quality (2026)
Last updated: June 2026
Mixed surface and groundwater across regions; chromium-6, nitrate and arsenic are recurring concerns, particularly in Central Valley agricultural areas.
Our California coverage focuses on the 8 metros below. Each city page lists the utility's water source, hardness in grains per gallon, contaminants flagged above EWG's stricter health guideline, and the whole-house system that fits that specific profile, not a generic recommendation copied across the state.
Common contaminants flagged across California
Across the California cities we cover, these are the contaminants most often reported above EWG's health guideline. None exceed federal EPA legal limits.
- nitrate
- arsenic
- 1,2,3-TCP
- chromium-6
- 13+ contaminants above EWG health guidelines
- High nitrate
- Arsenic
- Chromium-6
Cities we cover in California
| City | Hardness | Flagged above EWG guideline | Best fit |
|---|---|---|---|
| Bakersfield | - | nitrate, arsenic, 1,2,3-TCP | POU RO + softener |
| Fresno | Moderate | 13+ contaminants above EWG health guidelines, High nitrate, Arsenic | Reverse osmosis with nitrate-specific treatment |
| Los Angeles | Moderate–hard | Chromium-6, Disinfection byproducts (varies by district) | Softener + carbon filter |
| Riverside | - | chromium-6, perchlorate | Softener + carbon; POU RO for drinking |
| Sacramento | 3-7 | disinfection byproducts, chromium-6 | Catalytic carbon for chloramine |
| San Diego | 10-17 | chromium-6, disinfection byproducts, nitrate | Carbon for chloramine and DBPs, softener for scale |
| San Francisco | 2-5 | disinfection byproducts, lead service lines (older homes) | Carbon for chloramine; consider POU RO for older lead plumbing |
| San Jose | 5-12 | chromium-6 | Carbon + softener |
Recommended systems for California
Most California homes benefit from a layered setup: whole-house carbon for chlorine and taste, a softener if your CCR shows hardness above 7 gpg, and a certified under-sink RO at the kitchen tap if lead, PFAS, nitrate or arsenic are flagged.
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Find your system →California water FAQ
+Is California tap water safe to drink?
Yes, by federal standards: the cities on this page all meet every EPA legal limit. The contaminants we flag sit above EWG's stricter, non-enforceable health guideline, which is the benchmark most homeowners use when deciding whether to filter further at home.
+Why is California water hard?
Hardness comes from calcium and magnesium picked up as water moves through local geology. In California, the values vary city by city, see the table above for your metro. Anything above 7 grains per gallon is considered hard and is where a softener starts to make a noticeable difference.
+Do I need a softener or a filter in California?
Different problems, different tools. A whole-house carbon filter handles chlorine, chloramine and taste. A softener handles scale from hard water. Many California homes benefit from both, and a kitchen-tap RO if lead, PFAS or nitrate appear on your CCR.
Sources: EWG Tap Water Database