Rialto, CA Water Safety: 75/100 (2026)
2 ZIP codes · 5 water systems · Updated 2026-06-03
Within Rialto, safety indicators for tap water remain above the CA median — documented violations are infrequent and the city's compliance record sits in the upper tier.
How Rialto Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Rialto Water
- Homes built before 1986: 58% — older plumbing may contain lead solder.
- Estimated remediation: $2,200 per household.
- CDC health risk index: 11.58.
Who Supplies Your Water in Rialto
Federal records list 5 water systems tied to Rialto, CA. Of those, 3 are the primary providers, meaning service conditions, rate structures, and compliance histories can differ depending on where a property sits.
Overview
We track water quality and home safety data for 2 ZIP codes in Rialto, California (population ~105,846), covering 5 community water systems serving approximately 657,841 people region-wide.
No EPA violations recorded across any ZIP codes in Rialto — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Rialto: B (75/100)
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
Rialto water systems draw from: Surface water.
Lead & Copper
- Lead data: not yet available for Rialto
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 2 (Moderate Risk)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 2 ZIP codes
- Zone 3 (Low): 0 ZIP codes
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 92376 | B | West Valley Water District | 104,498 |
| 92377 | B | West Valley Water District | 104,498 |
All ZIP Codes in Rialto
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.
Health Outcomes in Rialto
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
Housing & Infrastructure in Rialto
With 58% 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
Plumbing risk in older housing is defined by two eras: the pre-1970 period when lead pipes were commonly used for service lines, and the 1970-to-1986 period when lead solder remained standard in copper plumbing until the federal ban. Rialto's median build year of 1977 lands in a range where both eras are heavily represented in the housing stock. That creates an elevated aggregate environment for plumbing-related lead exposure — one that city-level water quality averages don't capture, because the risk sits inside individual properties rather than in the distribution system.
Over half of homes in Rialto 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.
Cost Context: What Remediation Means for Rialto Homeowners
At current valuations, Rialto sits in the low remediation-share tier — the equity impact of fixing documented issues is proportionally minor.
Remediation costs in Rialto are relatively low compared to home values. The $1,200–$3,400 estimated range is a small fraction of median property value. Home values are 25% below the California average.
Lead Exposure Risk for Children in Rialto
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.
In recent monitoring under the Lead and Copper Rule, citywide samples for Rialto have approached or crossed the regulatory action level on multiple occasions. Combined with 58% of stock dating from the pre-rule era, the picture supports baseline single-tap reads as a standard household-level step.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Rialto
Across the NFIP's long tracking period, Rialto shows 5 claims and 100% 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.
Rialto has a moderate flood history with 5 FEMA claims averaging $1,138 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>$2,200</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 Rialto, CA