California Water Quality Rankings 2026: Best & Worst Cities

This page ranks the 163 California cities whose water systems we have matched to EPA records. Every city starts at 100 points and loses points for health-based EPA violations in the last five years (SDWIS 2026Q2), its most recent Lead and Copper Rule 90th-percentile result, PFAS detected in EPA's 2023–2026 UCMR5 monitoring, and 2012–2019 compliance samples that averaged near or above a limit. Letters follow fixed bands (A ≥90, B ≥80, C ≥70, D ≥60, F below 60). Cities run from the highest score (Los Angeles) down to the lowest (Yucaipa); ties are ordered by population served. See the full scoring methodology for every deduction and the data vintages. 30 further California cities are listed at the bottom without a grade because we have not yet matched them to an EPA water system.

What your city's grade means

An A or B grade points to water that consistently tests within federal safety limits, while a C suggests moderate issues worth watching and a D or F flags contaminants or compliance problems serious enough to act on. These grades describe system-level water leaving the treatment plant — they can't account for your home's own plumbing, so older houses with lead service lines or fixtures can add contaminants after the water arrives. For a contaminant-by-contaminant view, see the California contaminant breakdown or drill into the county-level rankings.

What California residents should do

• Find your city in the ranking below and open its full report for its violation history, lead results and PFAS table.
• See how California compares against the best-rated and worst-rated cities nationwide.
• Test your home's water if you have concerns — the most common issues involve lead, PFAS, and arsenic.
• Check whether your utility still has lead service lines in California — EPA's inventory counts lead pipes by water system, a risk that plant-level grades cannot capture. Read the lead guide for testing and filter options.
• If treatment makes sense for your situation, compare certified water filters matched to the contaminants found in your area.

This ranking covers 193 California cities. 163 of them are matched to an active EPA-registered community water system (PWSID). Those 161 systems report serving 26,480,664 people in EPA's Safe Drinking Water Information System (SDWIS).

Of 163 cities of the 193 California cities we can grade from EPA records, 113 cities (69%) grade B or better, 40 sit in the C range and 10 grade D or F. The average score is 89/100. 30 cities are not graded because they have not been matched to an EPA system yet.

EPA records 11 health-based violations in the last five years across 8 cities, and 5 cities still have a health-based violation listed as unresolved. Monitoring and reporting violations (35 in the same window) are paperwork lapses and cost far fewer points.

163 cities have a Lead and Copper Rule 90th-percentile result from 2020 or later: 4 cities at 5 ppb or more.

EPA's UCMR5 PFAS monitoring (2023–2026) covers 163 cities: PFAS were detected in 77 cities, and PFOA or PFOS reached EPA's 4 ppt limit in 61 cities.

Antioch scores highest (100) and Yucaipa lowest (34), a 66-point spread.

The clearest hard data for California is EPA's service line inventory, updated 2026-08-18 (Q2 2026). 4,260 California systems inventoried 10,071,272 service lines: 0 confirmed lead plus 12,918 galvanized lines requiring replacement, spread across 0 systems. Only 600,963 lines (6%) remain unverified, so California's inventory is comparatively complete.

Of the 161 city-linked California utilities with an inventory on file, 12 report at least one lead or galvanized-requiring-replacement line, 9 report none but still have a quarter or more of their lines unverified, and 140 report no lead with most lines verified. LOS ANGELES-CITY, DEPT. OF WATER & POWER, which serves Los Angeles and 3,875,566 people, is the biggest and reports no lead lines and 100% of lines verified non-lead.

Our California water guide flags arsenic, nitrates, chromium-6, and 1,2,3-trichloropropane as the contaminants of regional concern. Arsenic (EPA MCL 0.010 mg/L (10 ppb)) is linked to skin damage, circulatory problems and increased cancer risk; Nitrate (EPA MCL 10 mg/L (as nitrogen)) can cause methemoglobinemia ("blue baby syndrome") in infants under six months; Chromium (EPA MCL 0.1 mg/L for total chromium; no separate federal limit for chromium-6) can cause allergic dermatitis; the hexavalent form is a suspected carcinogen when ingested; Atrazine (EPA MCL 0.003 mg/L) is associated with cardiovascular and reproductive effects.

Source water explains a lot of the pattern in California. Disinfection byproducts are a surface-water signature: chlorine reacts with organic matter in rivers and reservoirs, so byproducts tend to run higher where systems chlorinate surface water. Arsenic is naturally occurring and tends to show up in groundwater, leaching from bedrock into aquifers rather than arriving from pollution. Nitrate and atrazine follow fertilizer, manure and septic loading, so they are most often a concern for systems drawing shallow groundwater in farm regions. Chromium and PFAS are tied to specific sites — industrial discharges, firefighting-foam use at airports and bases — rather than to geology, so contamination is local and can affect either source type. Your utility's Consumer Confidence Report names your source.

The best water quality in California is found in Los Angeles with a score of 100/100 and a grade of A. This puts Los Angeles among the top-performing cities in the country for drinking water safety.

The most concerning water quality is in Yucaipa scoring 34/100 with a grade of F. Residents may want to consider home water testing and filtration options.

The statewide average score is 89/100, which is 1 points above the national average of 88/100. Over half (61%) of California cities score above the national average, though some areas face challenges.