San Joaquin, CA Water Safety: 80/100 (2026)
1 ZIP code · 2 water systems · Updated 2026-06-03
The water systems supplying San Joaquin show a track record of above-average compliance with federal standards — consistently among the better performers in CA.
How San Joaquin Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for San Joaquin Residents
- Average lead level: 0.0062 mg/L.
- Homes built before 1986: 55% — older plumbing may contain lead solder.
- Estimated remediation: $2,900 per household.
- CDC health risk index: 12.33 — above typical levels.
San Joaquin's Water Providers
Structurally, San Joaquin, CA's water supply is divided. Federal data identifies 2 water systems in the area, with 2 providers serving the bulk of residential connections. These utilities operate independently, meaning rate-setting authority and EPA compliance accountability are distributed rather than centralized.
Overview
We track water quality and home safety data for 1 ZIP code in San Joaquin, California, covering 2 community water systems serving approximately 4,062 people.
No EPA violations recorded across any ZIP codes in San Joaquin — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for San Joaquin: B (80/100)
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
San Joaquin water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0062 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 2 (Moderate Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 93660 | B | Tranquillity Irrigation District | 807 |
All ZIP Codes in San Joaquin
- 93660 [B]
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.
San Joaquin 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
San Joaquin Infrastructure Age
With 55% 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
When more than half a city's housing predates the 1986 federal ban on lead solder, plumbing-era lead risk becomes a citywide concern rather than an exception. San Joaquin's median build year of 1986 places it squarely in that category.
Over half of homes in San Joaquin 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 San Joaquin
Looking at how documented remediation costs fit within San Joaquin property values, the equity share lands in the moderate tier — a finding that positions the household financial perspective between routine maintenance and a significant budget commitment, where most homeowners can successfully address documented issues by treating the expense as a planned financial priority rather than an unexpected one.
Remediation costs are moderate relative to home values in San Joaquin. The estimated $1,800–$4,800 range is manageable for most homeowners but still worth budgeting for. Home values are 63% below the California average.
San Joaquin: 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.
When older housing represents 55% of the local inventory or aggregate readings approach the federal action level, an in-home check becomes the standard way to translate citywide averages into the specific reality of an individual San Joaquin address.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
San Joaquin: Flood History & Water Damage Risk
The National Flood Insurance Program captures decades of claims at the local level, building a record of cumulative community flood exposure. For San Joaquin, that record documents 4 claims and 100% of ZIP codes inside FEMA-designated flood zones. What makes those numbers relevant to water quality is the set of mechanisms flooding activates: heavy precipitation that floods treatment intake zones can introduce contaminants upstream of normal filtration; well casings in low-lying areas can be infiltrated by floodwaters carrying bacteria, sediment, and chemical residue; and distribution system pressure changes during flooding can create backflow conditions. These effects become more probable as flood frequency and magnitude increase — and the NFIP record indicates both are meaningful factors locally.
San Joaquin has a moderate flood history with 4 FEMA claims averaging $92,576 per payout. 100% 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>$2,900</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 San Joaquin, CA