Onawa, IA: High Radon Risk — 70/100 (2026)
1 ZIP code · 1 water system · Updated 2026-06-03
Across Onawa, EPA monitoring data shows low violation rates and healthy safety margins — a pattern that places the city well above IA's average for drinking water compliance across recent reporting cycles.
How Onawa Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Onawa Water
- Average lead level: 0.002 mg/L.
- Homes built before 1986: 81% — older plumbing may contain lead solder.
- Estimated remediation: $3,000 per household.
- CDC health risk index: 14.98 — above typical levels.
Who Supplies Your Water in Onawa
Most residential addresses in Onawa, IA are served by a single water utility — the dominant system among the 1 provider tracked in federal data.
Overview
We track water quality and home safety data for 1 ZIP code in Onawa, Iowa, covering 1 community water system serving approximately 3,388 people.
No EPA violations recorded across any ZIP codes in Onawa — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Onawa: B (70/100)
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
Onawa water systems draw from: Groundwater.
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 1 (High 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 |
|---|---|---|---|
| 51040 | B | Onawa Municipal Water Plant | 2,906 |
All ZIP Codes in Onawa
- 51040 [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.
Health Outcomes in Onawa
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 Onawa
With 81% 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
Reading the housing age data for Onawa — median build year 1957 — the overriding implication is that the plumbing materials inside a typical home here reflect pre-1986 construction standards. In practical terms, that means lead-soldered copper joints are common across much of the housing stock. Where those materials are present, water can leach lead as it moves through joints — a pathway that corrosion control treatment under federal rules is designed to reduce, though it cannot eliminate lead risk where the plumbing materials themselves contain lead.
Over half of homes in Onawa 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 Onawa Homeowners
What should Onawa property owners understand before approaching remediation at this cost-to-value tier? That the equity share is elevated enough to treat this as a formal financial decision — one where knowing the full scope and prioritizing documented issues by urgency shape the outcome more than any single variable, given where this market falls on the remediation-share scale.
At 2.1% of home value, remediation costs in Onawa represent a significant financial burden. For homes valued near the median, fixing water and safety issues could cost $2,000–$4,000. Home values here are 15% below the Iowa average.
Lead Exposure Risk for Children in Onawa
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.
Pulling a tap sample fills the gap that utility data cannot close, particularly here where 81% of housing dates from the pre-rule era and citywide monitoring sits at or above the regulatory mark in Onawa.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in Onawa
NFIP records stretching across multiple decades show Onawa accumulating 6 claims and carrying 100% of its ZIP codes inside FEMA flood zones — evidence of meaningful exposure that extends beyond isolated incidents. The mechanisms linking flooding to water quality haven't changed: treatment facilities can be overwhelmed, wells can be infiltrated, and distribution systems can experience backflow. For a community at this exposure level, those mechanisms shift from hypothetical to periodically relevant.
Onawa has a moderate flood history with 6 FEMA claims averaging $25,344 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>$3,000</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 Onawa, IA