Rancho Cucamonga, CA: 15 Violations — 80/100 (2026)
5 ZIP codes · 4 water systems · Updated 2026-06-03
Across Rancho Cucamonga, EPA monitoring data shows low violation rates and healthy safety margins — a pattern that places the city well above CA's average for drinking water compliance across recent reporting cycles.
How Rancho Cucamonga Compares
Data: EPA SDWIS Last verified: 2026-06-03
Water Quality Map: Rancho Cucamonga, CA
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Score Distribution
Distribution of water safety grades across Rancho Cucamonga.
Rancho Cucamonga Water: The Quick Version
- Your city's water systems recorded 15 violations in the past 5 years.
- Average lead level: 0.002 mg/L.
- Homes built before 1986: 46% — older plumbing may contain lead solder.
- Estimated remediation: $1,360 per household.
- CDC health risk index: 11.58.
Water Systems Serving Rancho Cucamonga
Rancho Cucamonga, CA is covered by 3 major water utilities out of 4 federally tracked systems, each managing its own pipes, treatment processes, and EPA filings. What a household gets from the tap depends on which provider's system serves that address.
Overview
We track water quality and home safety data for 5 ZIP codes in Rancho Cucamonga, California (population ~174,808), covering 4 community water systems serving approximately 449,246 people region-wide.
5 of 5 ZIP codes (100%) have recorded EPA violations. All violations are monitoring/reporting type.
Home Safety Score
Average Home Safety Score for Rancho Cucamonga: 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
Rancho Cucamonga water systems draw from: Groundwater, Surface water.
Lead & Copper
- Average lead level (90th percentile): 0.0020 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)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 5 ZIP codes
- Zone 3 (Low): 0 ZIP codes
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Lead | Inorganic | 6 | 5 |
| Stage 1 DBP Rule | Treatment Technique | 6 | 5 |
| Consumer Confidence Report Rule | Reporting | 6 | 5 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 91701 | B | 3 | 0 | Cucamonga Valley Water District |
| 91729 | B | 3 | 0 | Cucamonga Valley Water District |
| 91730 | B | 3 | 0 | Cucamonga Valley Water District |
| 91737 | B | 3 | 0 | Cucamonga Valley Water District |
| 91739 | B | 3 | 0 | Cucamonga Valley Water District |
All ZIP Codes in Rancho Cucamonga
- 91701 [B] — 3 violations
- 91729 [B] — 3 violations
- 91730 [B] — 3 violations
- 91737 [B] — 3 violations
- 91739 [B] — 3 violations
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.
CDC Health Data for Rancho Cucamonga
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
Key Contaminants Detected in Rancho Cucamonga
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
How Old Is Rancho Cucamonga's Housing Stock?
With 46% 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 construction carries elevated plumbing-era lead risk because lead solder was widely used before that federal ban. In Rancho Cucamonga, the median build year of 1991 indicates a housing stock where that older fraction represents a significant share of the residential inventory.
Most homes in Rancho Cucamonga were built after 1986, reducing the risk of lead contamination from plumbing. Older homes should still be tested.
Source: U.S. Census Bureau ACS B25034.
Rancho Cucamonga: Remediation Cost in Perspective
Equity impact data for Rancho Cucamonga lands in the favorable tier — remediation claims a small slice of what properties here are worth.
Remediation costs in Rancho Cucamonga are relatively low compared to home values. The $640–$2,240 estimated range is a small fraction of median property value. Home values are 14% above the California average.
Protecting Children from Lead in Rancho Cucamonga
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.
Older stock in Rancho Cucamonga represents 46% of the inventory, and citywide monitoring runs at or above the federal action level — making an in-home read a standard household-level step.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Climate-Related Water Risk for Rancho Cucamonga
Within the NFIP's national dataset, Rancho Cucamonga falls in moderate-exposure territory — 47 documented incidents spanning multiple decades, with 80% of local ZIP codes sitting inside FEMA flood boundaries. That combination warrants inclusion in any thorough local water quality review.
Rancho Cucamonga has a moderate flood history with 47 FEMA claims averaging $3,104 per payout. 80% 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>$1,360</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 Rancho Cucamonga, CA