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Not health advice. Contact your local water utility for concerns.
Data from EPA Water Quality Reports. For official information, contact your water utility or health department.
Water quality scores for 193 cities in California
It depends on your utility. 8 of the 163 California water systems we grade from EPA records have a health-based violation in the last five years; the state averages 89/100 (1 above the national 88). Lowest graded: Yucaipa (F). Highest: Los Angeles (A).
California's official certified-lab list, when to test well vs city water, typical lab prices, and how to take a first-draw lead sample.
Across the 163 California water systems we can grade from EPA records, the average score is 89/100 — 1 points above the U.S. national average of 88/100. 61% of graded California cities (99 of 163) score above that national benchmark, and 97 earn a Grade A. 8 cities have at least one health-based EPA violation in the last five years. 30 cities are not graded because we have not yet matched them to an EPA water system.
The contaminants most commonly flagged in California water systems are arsenic (naturally occurring in groundwater), nitrates (agricultural runoff) and chromium-6 (industrial pollution). See the full breakdown in our California water quality rankings or compare against the cities with the best water quality in America.
See the top 20 cities with the cleanest, safest drinking water
Complete water quality rankings for every city in California
3,875,566 residents
1,385,379 residents
666,581 residents
466,772 residents
344,000 residents
277,668 residents
237,700 residents
208,129 residents
200,232 residents
198,000 residents
175,396 residents
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170,236 residents
168,289 residents
162,954 residents
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155,612 residents
137,044 residents
132,430 residents
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115,074 residents
110,000 residents
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33,300 residents
16,336 residents
13,486 residents
113,500 residents
94,738 residents
84,757 residents
66,809 residents
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93,980 residents
81,773 residents
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270,000 residents
164,344 residents
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68,871 residents
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32,697 residents
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444,800 residents
86,435 residents
84,292 residents
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169,455 residents
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214,665 residents
126,804 residents
78,376 residents
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41,193 residents
248,000 residents
105,603 residents
79,776 residents
51,428 residents
168,575 residents
80,824 residents
201,000 residents
90,911 residents
81,998 residents
66,135 residents
51,361 residents
47,475 residents
33,828 residents
66,600 residents
89,947 residents
54,453 residents
32,547 residents
31,176 residents
298,398 residents
84,928 residents
1,039,920 residents
110,044 residents
78,025 residents
74,877 residents
15,437 residents
99,650 residents
93,692 residents
66,967 residents
527,979 residents
310,539 residents
294,090 residents
267,881 residents
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174,226 residents
148,496 residents
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120,770 residents
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110,556 residents
100,744 residents
89,628 residents
76,689 residents
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72,624 residents
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68,272 residents
66,045 residents
65,231 residents
56,793 residents
50,381 residents
348,593 residents
46,525 residents
26,554 residents
20,188 residents
40,600 residents
545,716 residents
188,784 residents
151,713 residents
146,147 residents
130,130 residents
120,377 residents
53,355 residents
60,414 residents
62,183 residents
185,010 residents
59,203 residents
218,771 residents
191,302 residents
63,487 residents
52,010 residents
873,965 residents
No EPA water-system match yet — no score.
208,634 residents
No EPA water-system match yet — no score.
177,603 residents
No EPA water-system match yet — no score.
124,321 residents
No EPA water-system match yet — no score.
116,241 residents
No EPA water-system match yet — no score.
110,763 residents
No EPA water-system match yet — no score.
110,051 residents
No EPA water-system match yet — no score.
106,098 residents
No EPA water-system match yet — no score.
104,677 residents
No EPA water-system match yet — no score.
102,527 residents
No EPA water-system match yet — no score.
99,561 residents
No EPA water-system match yet — no score.
95,638 residents
No EPA water-system match yet — no score.
93,002 residents
No EPA water-system match yet — no score.
91,008 residents
No EPA water-system match yet — no score.
79,827 residents
No EPA water-system match yet — no score.
74,559 residents
No EPA water-system match yet — no score.
71,576 residents
No EPA water-system match yet — no score.
71,329 residents
No EPA water-system match yet — no score.
70,127 residents
No EPA water-system match yet — no score.
69,757 residents
No EPA water-system match yet — no score.
64,355 residents
No EPA water-system match yet — no score.
61,271 residents
No EPA water-system match yet — no score.
61,027 residents
No EPA water-system match yet — no score.
56,930 residents
No EPA water-system match yet — no score.
55,931 residents
No EPA water-system match yet — no score.
55,364 residents
No EPA water-system match yet — no score.
52,176 residents
No EPA water-system match yet — no score.
49,087 residents
No EPA water-system match yet — no score.
44,190 residents
No EPA water-system match yet — no score.
42,287 residents
No EPA water-system match yet — no score.
California faces unique water quality challenges due to its diverse geography, agricultural industry, and recurring droughts. The state's water supply comes from a complex system of reservoirs, aqueducts, and groundwater basins that serve over 39 million residents. Water quality varies significantly across the state, with some communities facing serious contamination issues while others enjoy excellent tap water.
Across the 163 California cities graded from EPA records, the average water quality score is 89/100. 10 cities score below 70 (D or F) because of health-based violations, lead results, PFAS or historical readings near a limit. The highest-rated city is Los Angeles with a score of 100/100, while Yucaipa has the most room for improvement at 34/100.
10 of the 163 California cities we grade score below 70/100. If your city is one of them — or you just want extra protection — a certified filter is the fastest way to reduce exposure. The findings that drag a score down (lead, PFAS, arsenic, nitrate) are exactly the ones a basic carbon pitcher does not remove.
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California draws water from multiple sources including the Sierra Nevada snowpack, the Colorado River, local groundwater aquifers, and desalination plants. The State Water Project and Central Valley Project transport water across hundreds of miles. Groundwater provides approximately 40% of the state's water supply during normal years and up to 60% during droughts.
These contaminants have been detected in various California water systems
California often sets stricter water quality standards than federal EPA requirements. The State Water Resources Control Board oversees drinking water programs, and California has been a leader in establishing standards for emerging contaminants. The state's Proposition 65 requires disclosure of chemicals known to cause cancer or reproductive harm.
Central Valley communities face particular challenges with nitrate contamination from agricultural activities. Some disadvantaged communities rely on contaminated groundwater without access to treatment. Wildfire ash can temporarily affect water quality in affected watersheds. Lead in older pipes remains a concern in some urban areas.
California residents should review their annual Consumer Confidence Reports, consider whole-house filtration in areas with known contamination, and support local water infrastructure investments. Reverse osmosis systems are effective against most California contaminants including arsenic and chromium-6.
Most California cities we grade have tap water in good standing with EPA. With an average score of 89/100 across 163 graded cities, California generally has good water quality. However, water quality varies by utility, so check your specific city's report.
The most common water quality concerns in California include arsenic (naturally occurring in groundwater), nitrates (agricultural runoff), chromium-6 (industrial pollution). These contaminants can come from natural sources, industrial activities, or aging infrastructure. Review your city's specific report to see which contaminants affect your area.
Whether you need a water filter depends on your specific location and health concerns. With 10 California cities grading D or F on EPA records, residents in those areas may benefit from filtration. Look for filters certified by NSF/ANSI to remove the specific contaminants found in your area.
Public water systems in California are required to provide annual Consumer Confidence Reports (CCRs) to residents. You can usually find your report on your water utility's website, request it by phone, or access it through the EPA's database. Our city-level reports above summarize key information from these official sources.
Lead can be present in California water, primarily from older plumbing infrastructure. Homes built before 1986 may have lead pipes or lead solder. While water treatment plants remove lead, it can leach into water from service lines and home plumbing. Check your city's specific report for lead testing data, and consider having your tap water tested if you live in an older home.
PFAS ("forever chemicals") have been detected in water systems across the United States, including in California. These chemicals are associated with industrial sites, military bases, and firefighting foam use. The EPA has set new PFAS limits effective 2024. Check individual California city reports for PFAS testing results in your area.
On EPA records, Los Angeles has the highest water quality score in California at 100/100 (Grade A). However, "best" depends on your specific health concerns. View our Best Water Quality in California page for a complete ranking.
Public water systems in California are required by the EPA to test water regularly. Testing frequency depends on the contaminant: bacteria testing occurs daily to weekly, while chemical contaminants may be tested quarterly or annually. Results are published in annual Consumer Confidence Reports. Our site aggregates this data from EPA's SDWIS database.
Compare water quality across counties and find data for your area