Is Modesto, CA tap water safe?
Supplied by City of Modesto · serves 218,915 people (70,877 connections) · Purchased surface water · EPA ID CA5010010
Data: U.S. EPA · How we read the data · How we check it
Most of Modesto gets its water from City of Modesto. Parts of the city are served by 10 smaller systems: City of Modesto – Salida (14,576 people), City of Waterford (8,788 people), City of Modesto – del Rio (1,346 people), City of Modesto – South Turlock (1,109 people) and 6 more. Your water bill names your system.
Buys water from Modesto Irrigation District. Treated water bought from another system can carry that system's contaminants.
Summary
PFAS above the 2024 federal limits. Systems have until 2029 to meet the PFAS limits.
Is it an emergency? No: PFAS limits are about years of exposure, not a glass of water, and nothing in EPA's data calls for you to stop drinking the water today. If your utility ever issues a boil-water or do-not-drink notice, follow it.
- PFAS
- Above limitPFOA, PFOS above the federal limit in EPA's 2023–2025 testing (PFOA 5.85 ppt vs a limit of 4 ppt, PFOS 18.5 ppt vs a limit of 4 ppt, where ppt = parts per trillion).
- Lithium
- Above screening levelHighest result 21 ppb. EPA uses 10 ppb to decide what to study further. It is not a health limit, and there is no federal limit for lithium. About 1 in 4 systems tested were above it.
- Lead
- Near 2027 action level12 ppb (parts per billion) at the 90th percentile: 9 in 10 homes sampled were at or below it. Action level 15 ppb, falling to 10 ppb in Nov 2027. Monitoring period Jan 2025 – now, still in progress (results reported so far). Your home's pipes can make yours higher.
- Violations
- None health-basedNo health-based violations since 2016.
- Pregnant, or mixing baby formula with tap water? Babies drink more water for their size, so PFAS exposure matters more for them. Consider bottled water or a filter certified for PFAS for formula, and ask your doctor. Health effects.
- To lower your PFAS exposure now, a home filter certified for PFAS reduction works (reverse osmosis, or activated carbon certified to NSF/ANSI 53 or 58). Filters for these results.
- Built before 1986, or not sure what your service line is made of? Check your service line and test your tap. Utility data can't show your pipes.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read City of Modesto's 2026 water quality report (Consumer Confidence Report, from the utility). It lists every regulated contaminant tested, including ones not on this page. Questions: (209) 342-4592.
PFAS (“forever chemicals”)
EPA UCMR 5: 42 entry points tested Nov 2023 to Sep 2024. "Average" is the highest entry-point average (non-detects counted as zero), the way EPA compares UCMR 5 results to the limits. ppt = parts per trillion. These results do not determine compliance.
| Contaminant | Highest average |
|---|---|
| PFOA Above limit Limit 4 ppt | 5.85 ppt 1.46× the limit |
| PFOS Above limit Limit 4 ppt | 18.5 ppt 4.63× the limit |
| PFHxS Detected, below limit Limit 10 ppt | 6.75 ppt 68% of the limit |
| PFNA Not detected Limit 10 ppt | – |
| HFPO-DA (GenX) Not detected Limit 10 ppt | – |
| Hazard Index (a combined score for PFHxS, PFNA, GenX and PFBS, where above 1 is over the limit) Detected, below limit Limit 1 | 0.68 |
| PFBS Detected, below limit Guideline 2,000 ppt | 2.15 ppt |
| PFBA Not detected Guideline 6,000 ppt | – |
| PFHxA Detected, below limit Guideline 3,000 ppt | 3.85 ppt |
| PFPeA Detected, no limit | 4.15 ppt |
| PFHpA Detected, no limit | 1.8 ppt |
For context: the PFOA average is higher than at 91% of the California systems EPA tested and the PFOS average is higher than at 95% of the California systems EPA tested.
29 PFAS tested, 7 detected at least once. "Not detected" means below EPA's reporting limit (about 2 to 20 ppt depending on the chemical), not proven zero. PFAS not listed were not detected. The limits for PFHxS, PFNA, GenX and the Hazard Index were proposed for rescission in May 2026. That proposal is not final. Systems have until 2029 to meet the limits.
Lithium
Detected in 13 of 86 samples. Highest result 21 ppb. EPA's non-enforceable screening level is 10 ppb. Above screening level The screening level is how EPA decides what to study further, not a health limit. There is no federal limit for lithium and no filter is certified to remove it. About lithium.
Lead and copper
Latest 90th percentile: 12 ppb lead (Jan 2025 – now (in progress)). Near 2027 action level
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2025 – now (in progress) | 12 ppb |
| Jan 2022 – Dec 2024 | 0 ppb |
| Jan 2021 – Dec 2023 | 0 ppb |
Earlier results (9)
| Jan 2019 – Dec 2021 | 0 ppb |
| Jan 2016 – Dec 2018 | 0 ppb |
| Jan 2013 – Dec 2015 | 0 ppb |
| Jan 2010 – Dec 2012 | 0 ppb |
| Jan 2007 – Dec 2009 | 2.5 ppb |
| Jan 2006 – Dec 2006 | 1.2 ppb |
| Jan 2005 – Dec 2005 | 2.5 ppb |
| Jan 2003 – Dec 2005 | 2.5 ppb |
| Jan 2003 – Dec 2003 | 2.5 ppb |
Lead comes from pipes and fixtures, not the source water, so it varies home to home. The 90th percentile means 9 in 10 sampled homes were at or below it. More on lead.
Violations
Health-based violations mean a contaminant exceeded a limit or a required treatment step was missed. Monitoring and reporting violations mean required tests or reports were late or missing, so the water's quality during that time is unknown. The total includes every violation in EPA's records, most of them paperwork.
Earlier EPA testing (2013–2020)
| Contaminant | Highest | Guideline |
|---|---|---|
| Manganese | 110 ppb | 300 ppb |
| Vanadium | 54 ppb | 21 ppb |
| 1,2,3-Trichloropropane (TCP) | 0.14 ppb | 0.0004 ppb |
| Strontium | 1.8 ppm | 1.5 ppm |
| Chlorate | 960 ppb | 210 ppb |
| Chromium-6 | 7 ppb | – |
| 1,4-Dioxane | 0.17 ppb | 0.35 ppb |
| Molybdenum | 9.7 ppb | 40 ppb |
Where it serves
Modesto
ZIP codes the system reported serving: 95350, 95351, 95352, 95353, 95354, 95355, 95356, 95357, 95358
Nearby utilities
- City of Ceres Ceres · 3 mi · PFAS above limit
- City of Ripon Ripon · 10 mi · PFAS above limit
- City of Turlock Turlock · 12 mi
- City of Manteca Manteca · 16 mi · PFAS above limit
- City of Lathrop Lathrop · 21 mi · PFAS above limit
- City of Tracy Tracy · 25 mi
Questions
Is Modesto tap water safe to drink?
Most of Modesto gets its water from City of Modesto. City of Modesto has no health-based violations since 2016. EPA testing found PFAS above the 2024 federal limits, which systems must meet by 2029. Federal data can't tell you about your own pipes: lead comes from service lines and plumbing, so test your tap if your home was built before 1986. For the official word, read the utility's annual Consumer Confidence Report.
Does Modesto water have PFAS?
Yes. EPA's 2023–2025 testing of City of Modesto found 7 PFAS at least once. The highest entry-point averages were above the federal limit for PFOA and PFOS: PFOA 5.85 ppt, PFOS 18.5 ppt (limit 4 ppt for PFOA and PFOS, 10 ppt for the others).
What is the lead level in Modesto water?
The most recent 90th-percentile lead result for City of Modesto is 12 ppb, for the monitoring period that began Jan 2025 (still in progress). The federal action level is 15 ppb, falling to 10 ppb in November 2027. The 90th percentile means 9 in 10 homes sampled were at or below this number. Individual homes can be higher.
Check these numbers yourself
Every figure on this page comes from public EPA records. You don't have to take our word for it:
- EPA's own report for CA5010010: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID CA5010010).
- EPA SDWIS download: the lead results, population and violation records we use.
- City of Modesto's 2026 water quality report: the utility's own annual report, including contaminants EPA's national database doesn't carry (link checked Nov 14, 2026). Phone: (209) 342-4592.
- City of Modesto website
Found something that doesn't match? Tell us and we'll check it against EPA's records. How we check our data.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.