B69/100
Modesto Tap Water Quality: Is It Safe to Drink? (2026 Report)
Serving 235,734 residents · California
What's In Modesto's Tap Water?
76
Contaminants Tested
2
Exceed EPA Limits
1
Above EPA Goals
3 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
PFOS | 0.005 µg/L | 0.004 µg/L | Over Limit |
PFOA | 0.004 µg/L | 0.004 µg/L | Over Limit |
chlorate | 960.00 µg/L | — | Above Goal |
EPA Violation History
No violations in the past 5 years
Full EPA compliance since 2013.
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Water Utility Details
CITY OF MODESTO - SALIDA
Population Served
14,537
Water Source
Groundwater
System ID
CA5010005
MODESTO, CITY OF
Population Served
218,771
Water Source
Purchased Surface Water
System ID
CA5010010
CITY OF MODESTO - SOUTH TURLOCK
Population Served
1,099
Water Source
Groundwater
System ID
CA5010023
CITY OF MODESTO - DEL RIO
Population Served
1,327
Water Source
Groundwater
System ID
CA5010029
Frequently Asked Questions About Modesto Water
Is Modesto tap water safe to drink?
Modesto, California tap water receives a grade of B (69/100), which is considered good. Out of 76 contaminants tested, 2 exceed EPA maximum contaminant levels (MCLs) and 4 exceed health guidelines (MCLGs). While the water meets federal standards, some residents may still choose to use a filter for additional peace of mind.
What contaminants are in Modesto's water?
Of the 76 contaminants tested in Modesto's water supply, the most notable include PFOS, PFOA, chlorate, vanadium. 2 contaminant(s) exceed EPA legal limits (MCLs). 4 contaminant(s) exceed EPA health goals (MCLGs), which are non-enforceable targets set at levels with no known health risk.
Does Modesto have any water quality violations?
Yes, Modesto has 32 EPA violation(s) on record, with the most recent in 2015. Violation types include MCL, Other, MR. 17 of these are health-based violations, which are the most serious category.
Do I need a water filter in Modesto?
Based on EPA data, using a water filter in Modesto is recommended. 2 contaminant(s) exceed legal limits. An NSF-certified filter — such as a reverse osmosis or activated carbon system — can effectively reduce many common contaminants. Choose a filter certified to remove the specific contaminants found in your area.
Where does Modesto's tap water come from?
Modesto's drinking water is sourced from groundwater and supplied by CITY OF MODESTO - SALIDA and 3 other water system(s). The system serves approximately 235,734 people. Groundwater is pumped from underground aquifers, which often provides natural filtration.
How often is Modesto's water tested?
Under the Safe Drinking Water Act (SDWA), water utilities are required to regularly test for over 90 contaminants. Testing frequency varies by contaminant — some are tested monthly, others quarterly or annually. Modesto's water systems must report results to the EPA and publish an annual Consumer Confidence Report (CCR). The data on this page reflects the latest available EPA testing data.
How does Modesto's water compare to other cities in California?
Modesto's water quality score of 69/100 earns a grade of B, which is considered good. This is an above-average score compared to many cities nationwide. Visit our California state page to see how all cities in the state compare.
What should I do if I'm concerned about Modesto's water quality?
If you have concerns about Modesto's tap water, consider these steps: (1) Request your utility's annual Consumer Confidence Report for detailed local data. (2) Get your water independently tested through a state-certified laboratory. (3) Consider an NSF-certified water filter rated for the contaminants found in your area. (4) Contact your water utility (CITY OF MODESTO - SALIDA) with specific questions. (5) Report water quality issues to your state drinking water program or the EPA Safe Drinking Water Hotline at 800-426-4791.