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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.
Comprehensive water safety analysis • Updated June 2026
San Jose's water quality score of 47/100 falls below average, with 1 contaminants at concerning levels.
•All 4 historical violation(s) in San Jose have been resolved.
Caution Advised. We recommend using a certified water filter. Score: 47/100.
Want to understand your score better? Learn how scores are calculated →
Is your neighbor's water better? See how San Jose's grade of F (47/100) stacks up.
Guides matched to the contaminants found in your water
Above 50% of EPA limits
| Contaminant | Level Detected | EPA Limit | % of Limit | Status |
|---|---|---|---|---|
| Total Trihalomethanes | 44.82 ug/L | 80.00 ug/L | 56.0% | Warning |
8 contaminants tested • EPA SDWIS data • Click any contaminant for details
| Contaminant | Level Detected | EPA Limit | % of Limit | Status |
|---|---|---|---|---|
| Total Trihalomethanes | 44.82 ug/L | 80.00 ug/L | 56.0% | Warning |
| Nitrate | 4.45 mg/L | 10.00 mg/L | 44.5% | Safe |
| Nitrite | 0.347 mg/L | 1.00 mg/L | 34.7% | Safe |
| Haloacetic Acids | 18.30 ug/L | 60.00 ug/L | 30.5% | Safe |
| Lead | 0.0042 mg/L | 0.015 mg/L | 28.3% | Safe |
| Chromium | 0.027 mg/L | 0.100 mg/L | 27.3% | Safe |
| Copper | 0.353 mg/L | 1.30 mg/L | 27.1% | Safe |
| Fluoride | 0.816 mg/L | 4.00 mg/L | 20.4% | Safe |
Based on EPA data, San Jose's water quality is below average. A certified water filter can significantly reduce your exposure to harmful contaminants.
See water filters that remove these contaminants →Based on detected contaminants in your water
There is no safe level of lead exposure. An NSF 53 certified filter or reverse osmosis system is strongly recommended.
Get APEC RO System (Removes 99% Lead) — ~$200 on AmazonRemoves chlorine, improves taste, and filters many organic compounds. Great starting point.
| Filter Type | Best For | Typical Price |
|---|---|---|
| Reverse Osmosis | Lead, PFAS, arsenic, nitrates (95-99% removal) | $150-300 |
| Under-sink carbon block | Chlorine, VOCs, many organics; some lead/PFAS models | $100-250 |
| Pitcher / faucet carbon | Chlorine, taste; NSF 53 models also reduce lead | $20-50 |
See our full water filter comparison for certified products matched to specific contaminants.
Our data covers your city's water system, but contaminants can vary at the tap. A home water test gives you exact results for your faucet.
Get a Certified Home Water Test — Tap ScoreWe may earn a commission when you purchase through our links, at no extra cost to you. All recommendations are based on our independent analysis of San Jose's water quality data.
Specific to the contaminants found in San Jose's EPA-reported water data
Lead has been detected in San Jose's water supply. There is no safe level of lead exposure. In children, lead can cause developmental delays, learning difficulties, irritability, weight loss, hearing loss, and seizures. In adults, lead exposure contributes to cardiovascular problems, decreased kidney function, and reproductive issues. Pregnant women exposed to lead can transfer it to their developing fetus, increasing risk of premature birth and reduced growth. Use an NSF 53 certified filter and run cold water before drinking to reduce exposure.
Elevated nitrate levels in San Jose's water pose particular risk to infants under six months. Nitrates can cause methemoglobinemia ("blue baby syndrome"), a condition where the blood cannot carry sufficient oxygen. Symptoms include bluish skin color, shortness of breath, and in severe cases, death. Formula-fed infants are at greatest risk. Pregnant women should also limit nitrate exposure. Boiling water does NOT remove nitrates—it actually concentrates them. Reverse osmosis or distillation systems effectively remove nitrates.
Past violations for San Jose's water system
other
Chromium - 2/4/2021
Resolvedreporting
Fluoride - 2/3/2025
Resolvedmonitoring
Chromium - 2/4/2024
Resolvedmonitoring
Mercury - 2/4/2022
ResolvedHow to contact your water provider and access official reports
The primary water provider for San Jose is SAN JOSE WATER SYSTEM (Public Water System ID: CA512249), serving approximately 1,012,356 residents. This utility is responsible for treating, testing, and delivering drinking water that meets EPA standards under the Safe Drinking Water Act. As a regulated public water system, it is required to conduct regular testing for over 90 contaminants and publish results in an annual Consumer Confidence Report (CCR) that must be made available to all customers by July 1 each year.
Your water utility is legally obligated to notify customers within 24 hours of any violation that poses an immediate health risk, and within 30 days for less urgent violations. If you are concerned about your water quality, you have the right to request testing data from your utility at any time. For independent verification, you can have your water tested at the tap by a state-certified laboratory. The EPA maintains a list of certified labs by state at epa.gov/dwlabcert. Home testing is particularly important because it captures contamination from your household plumbing that utility testing at distribution points would not detect.
San Jose Water Quality Score
Based on EPA contaminant data and compliance records
San Jose's water contains Total Trihalomethanes at 56% of the EPA limit.
Best for Lead Removal
APEC Reverse Osmosis System
Multi-stage RO reduces 99%+ of lead — the EPA-recommended treatment for lead.
Check Price on AmazonLower-cost alternative
ZeroWater 5-Stage Pitcher
NSF 53 certified pitcher · ~$40
No-install option — NSF 53 certified for lead & chromium reduction.
Check Price on Amazon →Not sure what filter you need?
Get a lab-certified water test to know exactly what's in your tap water.
Test Your Water with Tap ScoreWe may earn a commission when you purchase through our links, at no extra cost to you.
Based on contaminants detected in your water, these resources may be helpful:
Find the right filter for your San Jose water quality needs:
Understand the contaminants that may be present in San Jose's water supply and their health effects.
Matched to the contaminants actually detected in San Jose's water
Lead was detected in San Jose's water — an NSF 53 certified filter or reverse osmosis system removes up to 99% of it.
We may earn a commission when you purchase through our links, at no extra cost to you.
Understand your water better with our in-depth guides on contaminants, filtration, and water safety.
San Jose's drinking water is managed by SAN JOSE WATER SYSTEM, which serves approximately 1,012,356 residents through a combination of surface and groundwater sources. Our analysis of 8 tested contaminants reveals a quality score of 47/100, placing San Jose below the state average, suggesting room for improvement.
While San Jose's water meets all EPA maximum contaminant levels, 1 contaminant is present at elevated levels (above 50% of EPA limits). This doesn't necessarily indicate a health risk, but residents who want additional protection may benefit from a home water filter.
San Jose's water system has 4 documented EPA violations in its compliance history. All have since been resolved, indicating the utility has addressed past issues. Compliance history is one of the factors in our scoring methodology.
This report is based on data from the EPA Safe Drinking Water Information System (SDWIS) and the EPA Enforcement and Compliance History Online (ECHO) database. Our scoring algorithm weighs contaminant analysis (50%), compliance history (30%), and infrastructure factors (20%). Data is sourced directly from public EPA records and Consumer Confidence Reports. We are an independent resource with no affiliation to water utilities or government agencies. Learn more about our methodology.
Common questions from San Jose, California residents about their drinking water
San Jose's tap water scores 47/100 (Grade F), which falls below the national average of approximately 72. Multiple contaminants are at elevated levels. We strongly recommend using a water filter or bottled water for drinking and cooking. Contact your water utility for the latest testing data and consider independent testing at your tap.
San Jose's water has been tested for 8 contaminants spanning inorganic chemicals, disinfection byproducts, organic compounds, radionuclides, and microorganisms. No contaminants exceed EPA limits, but 1 are at elevated levels above 50% of EPA Maximum Contaminant Levels, including Total Trihalomethanes. See the full contaminant breakdown table above for detailed measurements and EPA limit comparisons.
San Jose has a water quality score of 47/100, earning a grade of F. This score is calculated using EPA SDWIS data and weighs three factors: contaminant levels (50% of score), regulatory compliance history (30%), and infrastructure factors (20%). The national average is approximately 72/100. San Jose's score of 47 is 25 points below the national average, suggesting residents should take additional precautions such as using a water filter. Learn more about how scores are calculated.
Based on San Jose's water quality profile, we recommend a reverse osmosis (RO) system for the most comprehensive filtration. Lead has been detected, and RO systems remove over 99% of lead. A quality RO system costs approximately $150-300 and is installed under the kitchen sink. Even in cities with good water quality, a filter provides an additional layer of protection against contaminants that may enter water from your home's plumbing. View our water filter comparison guide for specific product recommendations.
San Jose's primary water system, SAN JOSE WATER SYSTEM (PWS ID: CA512249), sources water from a combination of surface and groundwater sources, which provides resilience in the water supply but means the utility must manage treatment for the different contamination profiles of each source type. This system serves approximately 1,012,356 residents.
Yes, lead has been detected in San Jose's water supply. The EPA has established that there is no safe level of lead exposure, making this a priority concern especially for households with children or pregnant women. Lead typically enters drinking water through corrosion of lead service lines and lead solder in household plumbing, particularly in homes built before 1986. To reduce exposure: always use cold water for drinking and cooking, flush the tap for 30 seconds to 2 minutes after periods of non-use, and install an NSF 53 certified filter. Consider having your water independently tested at the tap, as lead levels can vary significantly from house to house depending on plumbing age and condition.
Yes, San Jose's water system has 4 documented EPA violations in its compliance history. All violations have been resolved, indicating the utility has taken corrective action. Violations can include exceeding contaminant limits, failure to conduct required testing, or failure to properly notify customers. Water utilities are required by the Safe Drinking Water Act to address violations and notify affected customers. You can look up the full violation history through the EPA's ECHO database or by contacting your water utility directly.
There are several options for testing your water in San Jose. For the most comprehensive results, use a state-certified laboratory (find one at epa.gov/dwlabcert). Home test kits like Tap Score provide EPA-certified lab analysis with easy-to-understand results. Basic test strips available at hardware stores can screen for common parameters like chlorine, pH, hardness, and lead, though they are less accurate than laboratory testing. You can also request the latest testing data directly from SAN JOSE WATER SYSTEM. Testing at your tap is important because it captures contamination from your household plumbing that city-level monitoring at distribution points does not detect.