Onyx, CA Water Safety: 63/100 (2026)
1 ZIP code · 1 water system · Updated 2026-06-03
Onyx'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 Onyx Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Onyx Water
- Homes built before 1986: 80% — older plumbing may contain lead solder.
- Estimated remediation: $2,200 per household.
- CDC health risk index: 12.57 — above typical levels.
Who Supplies Your Water in Onyx
Consolidated water delivery characterizes Onyx, CA: among 1 system in federal records, one utility holds the dominant service position — carrying the rate-setting authority, the infrastructure obligations, and the EPA reporting burden for most residential addresses.
Overview
We track water quality and home safety data for 1 ZIP code in Onyx, California, covering 1 community water system serving approximately 739 people.
No EPA violations recorded across any ZIP codes in Onyx — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Onyx: 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
Onyx water systems draw from: Groundwater.
Lead & Copper
- Lead data: not yet available for Onyx
- 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 |
|---|---|---|---|
| 93255 | C | TRADEWIND WATER ASSOC. | 632 |
All ZIP Codes in Onyx
- 93255 [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.
Health Outcomes in Onyx
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 Onyx
With 80% 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 lead that enters tap water in older homes often comes not from the municipal supply but from the home's own plumbing — from solder used in copper joints before the 1986 federal ban, or from lead pipes installed before 1970. In Onyx, where the median build year is 1974, these older materials are widespread. More than half the residential stock predates the 1986 solder ban, and a significant fraction predates 1970 as well. For residents in those homes, the city-wide water quality picture is a less relevant frame than the specific materials inside their own walls and under their own street.
Over half of homes in Onyx 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 Onyx Homeowners
Given current Onyx property values, the remediation share falls in the moderate tier — an indicator that the household financial perspective here calls for advance planning rather than dismissal, with most homeowners positioned to address documented issues through deliberate budgeting rather than needing to treat remediation as a significant equity event or financial emergency.
Remediation costs are moderate relative to home values in Onyx. The estimated $1,200–$3,300 range is manageable for most homeowners but still worth budgeting for. Home values are 75% below the California average.
Lead Exposure Risk for Children in Onyx
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.
Reading the local data together points toward a structural gap that matters more here than in low-exposure communities. 80% of Onyx stock comes from the pre-rule era, and citywide monitoring either approaches or sits beyond the federal benchmark under Lead and Copper Rule sampling. A baseline kit fits the routine-diligence category, with certified filtration available via retailer networks where confirmed faucet results warrant additional measures.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Onyx
Insurance claims filed under FEMA's NFIP for Onyx remain modest — consistent with limited flood exposure and an environment where flood-related water quality disruptions stay infrequent. The mechanisms connecting flooding to water safety are real but require event conditions that rarely appear at this claim volume.
Onyx has a relatively low flood history with 1 FEMA claims on record. While risk is limited, severe weather events can still impact water infrastructure.
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.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
What You Can Do in Onyx
- 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 80% of homes built before 1986, lead solder is a real possibility.
Deep Dive Reports
Detailed analysis for Onyx, CA