Modesto, CA Water Safety: 95/100 (2026)
10 ZIP codes · 8 water systems · Updated 2026-06-04
Tap water monitoring data for Modesto shows a consistently clean picture in CA — few violations on record, compliance well above the median.
How Modesto Compares
Data: EPA SDWIS Last verified: 2026-06-04
Water Quality Map: Modesto, CA
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Score Distribution
Safety grade breakdown for Modesto's 10 ZIP codes.
Key Facts for Modesto Residents
- Average lead level: 0.0006 mg/L.
- Homes built before 1986: 67% — older plumbing may contain lead solder.
- Estimated remediation: $1,800 per household.
- CDC health risk index: 12.27 — above typical levels.
Modesto's Water Providers
Multiple utilities divide Modesto, CA's water service — 3 leading providers among 8 on the federal register.
Overview
We track water quality and home safety data for 10 ZIP codes in Modesto, California, covering 8 community water systems serving approximately 268,575 people.
No EPA violations recorded across any ZIP codes in Modesto — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Modesto: A (95/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Modesto water systems draw from: Groundwater, Surface water.
Lead & Copper
- Average lead level (90th percentile): 0.0006 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 0 ZIP codes
- Zone 3 (Low): 10 ZIP codes
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 95350 | A | City of Modesto, | 218,771 |
| 95351 | A | City of Modesto, | 218,771 |
| 95352 | A | City of Modesto, | 218,771 |
| 95353 | A | City of Modesto, | 218,771 |
| 95354 | A | City of Modesto, | 218,771 |
| 95355 | A | City of Modesto, | 218,771 |
| 95356 | A | City of Modesto, | 218,771 |
| 95357 | A | City of Modesto, | 218,771 |
| 95358 | A | City of Modesto, | 218,771 |
| 95397 | A | City of Modesto, | 218,771 |
All ZIP Codes in Modesto
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
Modesto Community Health Snapshot
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Modesto Infrastructure Age
With 67% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Pre-1986 plumbing is not a rare legacy case in Modesto — it's the dominant profile. The median build year of 1977 indicates a housing stock where lead-soldered copper joints are a common structural feature of residences across the city.
Over half of homes in Modesto were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
How Remediation Costs Compare in Modesto
Because property values in Modesto comfortably exceed estimated remediation costs, the equity impact here is proportionally small.
Remediation costs in Modesto are relatively low compared to home values. The $960–$2,750 estimated range is a small fraction of median property value. Home values are 46% below the California average.
Modesto: Lead Risk & Vulnerable Populations
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Despite citywide averages serving as the standard public reference point, those aggregates cannot resolve what is happening at one specific faucet — and where 67% of Modesto homes come from before the solder rule or where utility samples sit at or above the action mark, the gap between system data and faucet reality matters more than it does in lower-exposure communities. An in-home draw closes that gap, with certified filtration through retailer networks available where confirmed faucet results warrant additional measures.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Modesto: Flood History & Water Damage Risk
Across the NFIP's long tracking period, Modesto shows 88 claims and 70% of ZIP codes within FEMA-designated flood zones — figures that place it in moderate flood exposure territory. At this level, the water-quality implications of flooding — contaminated wells, stressed treatment intake, distribution backflow — move from theoretical edge cases to genuine periodic risks, particularly during higher-severity events.
Modesto has a moderate flood history with 88 FEMA claims averaging $21,377 per payout. 70% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$1,800</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
Deep Dive Reports
Detailed analysis for Modesto, CA