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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
See the top 20 cities with the cleanest, safest drinking water
Complete water quality rankings for every city in California
346,824 residents
51,988 residents
65,040 residents
57,232 residents
109,398 residents
67,539 residents
60,105 residents
1,386,932 residents
88,665 residents
126,181 residents
31,573 residents
68,103 residents
99,561 residents
178,127 residents
59,520 residents
99,818 residents
105,432 residents
104,026 residents
121,253 residents
91,750 residents
112,174 residents
49,087 residents
80,273 residents
218,464 residents
151,038 residents
162,954 residents
35,135 residents
55,931 residents
69,757 residents
115,517 residents
57,938 residents
32,613 residents
76,416 residents
74,559 residents
56,999 residents
84,292 residents
228,673 residents
94,396 residents
82,800 residents
87,665 residents
54,824 residents
119,881 residents
230,504 residents
90,440 residents
82,739 residents
59,173 residents
202,063 residents
67,973 residents
177,603 residents
93,076 residents
79,793 residents
55,364 residents
176,124 residents
70,265 residents
110,051 residents
524,943 residents
873,965 residents
61,271 residents
320,804 residents
134,605 residents
106,098 residents
54,372 residents
82,155 residents
93,002 residents
114,355 residents
72,589 residents
43,363 residents
56,464 residents
143,617 residents
196,543 residents
61,121 residents
79,676 residents
90,189 residents
69,625 residents
102,527 residents
79,263 residents
174,068 residents
152,750 residents
53,850 residents
147,478 residents
73,631 residents
79,499 residents
70,127 residents
54,358 residents
82,868 residents
52,558 residents
88,083 residents
49,133 residents
466,742 residents
52,850 residents
79,332 residents
48,280 residents
84,605 residents
91,739 residents
85,331 residents
70,117 residents
74,091 residents
70,363 residents
51,268 residents
92,590 residents
71,576 residents
163,542 residents
114,761 residents
93,000 residents
68,875 residents
101,638 residents
101,475 residents
275,487 residents
120,124 residents
105,965 residents
44,190 residents
314,998 residents
47,339 residents
73,403 residents
214,547 residents
307,670 residents
62,787 residents
64,355 residents
175,265 residents
138,699 residents
104,570 residents
60,037 residents
67,359 residents
126,683 residents
105,742 residents
80,454 residents
62,088 residents
155,805 residents
52,176 residents
60,170 residents
134,810 residents
53,733 residents
104,677 residents
85,239 residents
157,136 residents
116,241 residents
62,190 residents
542,107 residents
151,713 residents
71,329 residents
50,000 residents
124,321 residents
3,898,747 residents
42,287 residents
147,773 residents
64,292 residents
95,804 residents
69,389 residents
91,008 residents
102,386 residents
79,190 residents
111,901 residents
83,498 residents
62,697 residents
48,518 residents
61,379 residents
107,263 residents
80,276 residents
61,027 residents
198,711 residents
86,333 residents
208,634 residents
56,930 residents
49,417 residents
62,956 residents
58,447 residents
403,455 residents
49,707 residents
129,295 residents
85,858 residents
440,646 residents
78,845 residents
79,871 residents
310,227 residents
54,000 residents
51,720 residents
66,700 residents
115,382 residents
139,812 residents
115,291 residents
71,941 residents
173,516 residents
62,671 residents
95,638 residents
172,800 residents
127,134 residents
61,032 residents
110,763 residents
92,301 residents
1,013,240 residents
222,101 residents
97,477 residents
79,827 residents
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.
Based on our analysis of 193 cities in California, the average water quality score is 80/100. 35 cities have water quality scores below 70, indicating potential concerns that residents should be aware of. The highest-rated city is Alameda with a score of 44/100, while Anaheim has the most room for improvement at 98/100.
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 have tap water that meets EPA safety standards. With an average score of 80/100 across 193 cities we analyzed, California generally has good water quality. However, water quality varies by location, 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 35 cities in California showing elevated contaminant levels, 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.
Based on our analysis, Alameda has the highest water quality score in California at 44/100 (Grade F). 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