California Water Quality Report 2026

25 cities13,910,882 residentsUpdated March 2026

D66.8/100State Average
California has 25 cities in our database, serving approximately 13,910,882 residents. The average PurityMap score is 66.8/100 (Grade: D), which is 11.1 points below the US average of 77.9/100. San Francisco has the cleanest water (85/100) while Bakersfield scores lowest (55/100) due to PFAS detected, very hard water.
Is California Tap Water Safe to Drink?
Use Filtration

California tap water is use filtration based on our analysis of 25 water systems serving 13,910,882 residents. The average PurityMap score is 66.8/100 (Grade: D), which is 11.1 points below the national average.

  • PFAS detected in 21 of 25 cities (84%). Forever chemicals require reverse osmosis filtration.
  • 1 cities have lead at or above 5 ppb. Homes built before 1986 are at highest risk.
  • 17 cities (68%) have hard or very hard water (7+ GPG) which causes scale buildup and appliance damage.
  • 6 cities exceed the EPA secondary TDS guideline of 500 ppm, which affects taste and may indicate elevated minerals.
Our Recommendation

We recommend an under-sink reverse osmosis system for drinking water in PFAS-affected areas of California. RO removes 99%+ of PFAS, lead, and other contaminants. For hard water cities, add a whole-house softener.

All 25 cities in California meet EPA federal drinking water standards as of 2026. However, EPA standards set legal limits — not health goals. Many contaminants are detected at levels that are legal but may still pose long-term health risks according to independent health organizations like the EWG.
California at a Glance
66.8Avg Purity Score
9Avg Hardness (GPG)
Hard
21Cities with PFAS
17Cities with Hard Water
3Avg Lead (ppb)
366Avg TDS (ppm)

California is 11.1 points below the US average of 77.9/100. Hardness is 2.7 GPG above the US average of 6.3 GPG.

Best & Worst Water in California
Cleanest

San Francisco

85/100

Source: Hetch Hetchy Reservoir Tuolumne River

Most Concerns

Bakersfield

55/100

PFAS detected, very hard water

Cities with Most Water Concerns in California

Cities ranked by lowest score. Click any city for the full report and filter recommendations.

RankCityScoreHardnessLeadKey Issues
1Bakersfield 55/10010.8 GPG2.8 ppbPFAS (4.8 ppt), Very Hard (10.8 GPG)
2Riverside 58/10012.8 GPG3.5 ppbPFAS (3.2 ppt), Very Hard (12.8 GPG), TDS (530 ppm)
3San Bernardino 58/10014.5 GPG3.5 ppbPFAS (4.2 ppt), Very Hard (14.5 GPG), TDS (590 ppm)
4Moreno Valley 58/10013.0 GPG2.8 ppbPFAS (2.8 ppt), Very Hard (13.0 GPG), TDS (535 ppm)
5Fontana 58/10013.5 GPG3.0 ppbPFAS (3.5 ppt), Very Hard (13.5 GPG), TDS (555 ppm)
6San Diego 61/10016.3 GPG1.8 ppbPFAS (2.1 ppt), Very Hard (16.3 GPG), TDS (650 ppm)
7Chula Vista 61/10014.5 GPG2.0 ppbPFAS (1.9 ppt), Very Hard (14.5 GPG), TDS (590 ppm)
8Fresno 62/1005.1 GPG2.5 ppbPFAS (5.2 ppt)
9San Jose 63/1009.1 GPG4.2 ppbPFAS (3.5 ppt), Hard (9.1 GPG)
10Irvine 63/10011.2 GPG2.5 ppbPFAS (2.5 ppt), Very Hard (11.2 GPG)
Score Distribution

How California's 25 cities score on the PurityMap 0–100 scale:

Excellent (85–100)
4 cities
Good (70–84)
2 cities
Moderate (60–69)
14 cities
Poor (below 60)
5 cities
Largest Cities in California — Water Quality

Water quality for the most populated cities. Click any city for details.





















CityPopulationScoreHardnessKey Issues
Los Angeles4.0M 69/1007.0 GPGPFAS, Hard, Lead
San Diego1.4M 61/10016.3 GPGPFAS, Very Hard
San Jose1.0M 63/1009.1 GPGPFAS, Hard
San Francisco875K 85/1002.2 GPG—
Oakland700K 85/1004.2 GPG—
Fresno542K 62/1005.1 GPGPFAS
Sacramento525K 70/1003.2 GPGPFAS
Long Beach467K 66/1008.5 GPGPFAS, Hard
Bakersfield403K 55/10010.8 GPGPFAS, Very Hard
Anaheim350K 66/10010.4 GPGPFAS, Hard
Riverside315K 58/10012.8 GPGPFAS, Very Hard
Stockton313K 67/1004.8 GPGPFAS
Santa Ana310K 63/10010.8 GPGPFAS, Very Hard
Irvine308K 63/10011.2 GPGPFAS, Very Hard
Chula Vista274K 61/10014.5 GPGPFAS, Very Hard
Fremont231K 85/1004.0 GPG—
Santa Clarita229K 66/1009.5 GPGPFAS, Hard
San Bernardino222K 58/10014.5 GPGPFAS, Very Hard
Modesto218K 70/1006.2 GPGPFAS
Fontana215K 58/10013.5 GPGPFAS, Very Hard
Hard Water in California

17 of 25 cities (68%) in California have hard or very hard water (7+ GPG). San Diego has the hardest at 16.3 GPG. Cities: San Diego, San Bernardino, Chula Vista, Fontana, Moreno Valley, Riverside, Irvine, Huntington Beach. A water softener is recommended.

Hard Water Guide Softener Solutions
PFAS in California Water

PFAS have been detected in 21 of 25 cities (84%) in California. Highest: Fresno at 5.2 ppt. Affected: Fresno, Bakersfield, San Bernardino, Los Angeles, Anaheim, San Jose, Fontana, Riverside. A reverse osmosis filter is recommended.

PFAS Guide RO for PFAS
Lead in California Water

1 cities in California have lead at or above 5 ppb. Highest: Los Angeles at 5.0 ppb. No safe level of lead exists. Cities: Los Angeles.

Lead Guide Under-Sink Filters
High TDS in California

6 cities in California have TDS above 500 ppm. Cities: San Diego, Chula Vista, San Bernardino, Fontana, Moreno Valley. RO effectively reduces TDS.

RO Reduces TDS
Water Sources in California

Where California gets its drinking water, based on 25 water systems.





Source TypeCities% of Total
Groundwater1144%
Surface Water936%
Mixed (Ground + Surface)416%
Other14%
Recommended Filter for California

California has both PFAS (21 cities) and hard water (17 cities). RO for drinking water + softener for whole house.

All California Cities — Ranked
#CityPop.ScoreHardnessLeadPFASTDS
1Bakersfield403K 55/10010.8 GPG (Very Hard)2.8 ppb⚠️ Yes (4.8 ppt)450 ppm
2Riverside315K 58/10012.8 GPG (Very Hard)3.5 ppb⚠️ Yes (3.2 ppt)530 ppm
3San Bernardino222K 58/10014.5 GPG (Very Hard)3.5 ppb⚠️ Yes (4.2 ppt)590 ppm
4Moreno Valley212K 58/10013.0 GPG (Very Hard)2.8 ppb⚠️ Yes (2.8 ppt)535 ppm
5Fontana215K 58/10013.5 GPG (Very Hard)3.0 ppb⚠️ Yes (3.5 ppt)555 ppm
6San Diego1.4M 61/10016.3 GPG (Very Hard)1.8 ppb⚠️ Yes (2.1 ppt)650 ppm
7Chula Vista274K 61/10014.5 GPG (Very Hard)2.0 ppb⚠️ Yes (1.9 ppt)590 ppm
8Fresno542K 62/1005.1 GPG (Moderate)2.5 ppb⚠️ Yes (5.2 ppt)220 ppm
9Huntington Beach199K 63/10011.0 GPG (Very Hard)2.8 ppb⚠️ Yes (2.5 ppt)455 ppm
10Irvine308K 63/10011.2 GPG (Very Hard)2.5 ppb⚠️ Yes (2.5 ppt)465 ppm
11San Jose1.0M 63/1009.1 GPG (Hard)4.2 ppb⚠️ Yes (3.5 ppt)380 ppm
12Santa Ana310K 63/10010.8 GPG (Very Hard)3.8 ppb⚠️ Yes (3.0 ppt)445 ppm
13Long Beach467K 66/1008.5 GPG (Hard)4.8 ppb⚠️ Yes (3.1 ppt)370 ppm
14Anaheim350K 66/10010.4 GPG (Hard)3.2 ppb⚠️ Yes (3.7 ppt)430 ppm
15Santa Clarita229K 66/1009.5 GPG (Hard)2.5 ppb⚠️ Yes (2.2 ppt)395 ppm
16Oxnard202K 66/10010.5 GPG (Hard)2.5 ppb⚠️ Yes (3.2 ppt)435 ppm
17Glendale197K 66/1008.2 GPG (Hard)3.5 ppb⚠️ Yes (2.8 ppt)350 ppm
18Stockton313K 67/1004.8 GPG (Moderate)3.0 ppb⚠️ Yes (2.8 ppt)175 ppm
19Los Angeles4.0M 69/1007.0 GPG (Moderate)5.0 ppb⚠️ Yes (4.1 ppt)330 ppm
20Sacramento525K 70/1003.2 GPG (Soft)2.2 ppb⚠️ Yes (2.9 ppt)115 ppm
21Modesto218K 70/1006.2 GPG (Moderate)2.8 ppb⚠️ Yes (3.0 ppt)255 ppm
22Fremont231K 85/1004.0 GPG (Moderate)3.2 ppb✅ No115 ppm
23San Francisco875K 85/1002.2 GPG (Soft)2.0 ppb✅ No55 ppm
24Oakland700K 85/1004.2 GPG (Moderate)3.8 ppb✅ No120 ppm
25Santa Rosa178K 85/1003.8 GPG (Moderate)2.0 ppb✅ No130 ppm
Water Utilities in California

California has 25 utilities. Major: LA Dept of Water and Power, San Diego Public Utilities Department, San Jose Water Company, SF Public Utilities Commission, City of Fresno Department of Public Utilities.

Sources: Colorado River Owens Valley local groundwater, Colorado River and Sacramento Delta, Sacramento Delta and local groundwater, Hetch Hetchy Reservoir Tuolumne River, Kings River and groundwater.

Frequently Asked Questions
Which city has the best water in California?
San Francisco scores highest at 85/100. Source: Hetch Hetchy Reservoir Tuolumne River.
Which city has the worst water in California?
Bakersfield scores lowest at 55/100 due to PFAS detected, very hard water.
Is California water hard or soft?
Average hardness: 9.0 GPG (Hard). 2.7 GPG above the US average of 6.3 GPG. 17 of 25 cities have hard/very hard water.
Has PFAS been found in California water?
PFAS have been detected in 21 of 25 cities (84%) in California. Highest: Fresno at 5.2 ppt. Affected: Fresno, Bakersfield, San Bernardino, Los Angeles, Anaheim, San Jose, Fontana, Riverside. A reverse osmosis filter is recommended.
What water filter should I use in California?
California has both PFAS (21 cities) and hard water (17 cities). RO for drinking water + softener for whole house.
How does California water compare to the US average?
Score: 66.8/100 (11.1 points below US avg 77.9). Hardness: 9.0 GPG (2.7 GPG above US avg 6.3).
Where does California get its drinking water?Where does California get its drinking water?
California water comes from: Groundwater: 11 cities (44%), Surface Water: 9 cities (36%), Mixed (Ground + Surface): 4 cities (16%), Other: 1 cities (4%).
Data Sources & Methodology
  • EPA Safe Drinking Water Information System
  • EWG Tap Water Database
  • State utility Consumer Confidence Reports
  • USGS regional water monitoring data

PurityMap compiles publicly available data and does not perform independent testing.

How we analyze water Data sources
All California Cities with Water Reports

25 city water quality reports available for California.

25 Reports
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