Rio Oso, CA Water Safety: 63/100 (2026)
1 ZIP code · 1 water system · Updated 2026-06-03
Rio Oso's water quality grade in CA reflects a middle-ground assessment — service areas range from fully compliant to violation-flagged in current EPA records.
How Rio Oso Compares
Data: EPA SDWIS Last verified: 2026-06-03
Key Facts for Rio Oso Residents
- Homes built before 1986: 65% — older plumbing may contain lead solder.
- Estimated remediation: $1,600 per household.
- CDC health risk index: 12.28 — above typical levels.
Rio Oso's Water Providers
Water service in Rio Oso, CA is organized around a single utility — one of 1 tracked by regulator, and the one that manages the local distribution network while holding primary responsibility for EPA compliance reporting.
Overview
We track water quality and home safety data for 1 ZIP code in Rio Oso, California (population ~992), covering 1 community water system serving approximately 4,124 people region-wide.
No EPA violations recorded across any ZIP codes in Rio Oso — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Rio Oso: C (63/100)
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
Rio Oso water systems draw from: Groundwater.
Lead & Copper
- Lead data: not yet available for Rio Oso
- 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 |
|---|---|---|---|
| 95674 | C | CITY OF WHEATLAND | 4,124 |
All ZIP Codes in Rio Oso
- 95674 [C]
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.
Rio Oso 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
Rio Oso Infrastructure Age
With 65% 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
The character of Rio Oso's housing stock is one of deep historical layering — a median build year of 1973 signals a city built largely before the plumbing era changes of 1986 and 1970. Lead-soldered copper joints and, in the oldest properties, lead service lines are commonly present in this inventory. That context shapes what individual water testing may reveal, particularly in neighborhoods where the oldest housing is concentrated.
Over half of homes in Rio Oso 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 Rio Oso
In Rio Oso, the equity impact of remediation is proportionally small — not the kind of financial commitment that rises to the level of a genuine planning constraint, but a minor share of what most properties here are worth.
Remediation costs in Rio Oso are relatively low compared to home values. The $800–$2,600 estimated range is a small fraction of median property value. Home values are 20% below the California average.
Rio Oso: 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.
65% — that captures the slice of Rio Oso housing dating from before the federal ban on solder containing lead. It pairs with aggregate utility readings that either approach or cross 0.015 mg/L, the benchmark set under the EPA Lead and Copper Rule. Together, the two figures shift one-home reads into a standard household-level confirmation, particularly for families with kids. A certified lead-removal filter is available through retailer-verified channels if a kit returns results that warrant additional measures.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Rio Oso: Flood History & Water Damage Risk
100% of ZIP codes in Rio Oso are mapped into FEMA-designated flood zones, and the NFIP records 5 claims reflecting a multi-event flood history. That combination places local flood exposure in the range where water-quality implications deserve at least periodic attention.
Rio Oso has a moderate flood history with 5 FEMA claims averaging $9,739 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>$1,600</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.
What You Can Do in Rio Oso
- Test your water at home. City-level data shows averages — your tap may differ. NSF-certified test kits cost $20-40 and give results in days.
- Install a certified water filter. An NSF-certified pitcher or under-sink filter removes most common contaminants.
- Check your home's plumbing. With 65% of homes built before 1986, lead solder is a real possibility.
Deep Dive Reports
Detailed analysis for Rio Oso, CA