Marathon, IA: High Radon Risk — 66/100 (2026)
1 ZIP code · 1 water system · Updated 2026-06-03
If you're checking Marathon, IA tap water safety, the short answer is: average — violations are present in parts of the city and specifics depend on which water system serves your address.
How Marathon Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About Marathon Water
- Average lead level: 0.002 mg/L.
- Homes built before 1986: 86% — older plumbing may contain lead solder.
- Estimated remediation: $1,200 per household.
- CDC health risk index: 13.28 — above typical levels.
Who Supplies Your Water in Marathon
Most residential addresses in Marathon, 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 Marathon, Iowa, covering 1 community water system serving approximately 413 people.
No EPA violations recorded across any ZIP codes in Marathon — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for Marathon: C (66/100)
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
Marathon 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 |
|---|---|---|---|
| 50565 | C | Marathon Light & Water Department | 230 |
All ZIP Codes in Marathon
- 50565 [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 Marathon
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 Marathon
With 86% 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
Viewed through the lens of construction era, Marathon is predominantly an older city — a median build year of 1901 puts most of the residential inventory in the range where pre-1986 plumbing materials were the standard.
Over half of homes in Marathon 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 Marathon Homeowners
The Marathon equity share sits above the low tier but short of the range where remediation becomes a heavy financial burden — the cost-to-value ratio is moderate, and deliberate planning is the key practical lever for most homeowners.
Remediation costs are moderate relative to home values in Marathon. The estimated $800–$1,500 range is manageable for most homeowners but still worth budgeting for. Home values are 56% below the Iowa average.
Lead Exposure Risk for Children in Marathon
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 86% of housing dates from the pre-rule era and citywide monitoring sits at or above the regulatory mark in Marathon.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
What You Can Do in Marathon
- 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 86% of homes built before 1986, lead solder is a real possibility.
Deep Dive Reports
Detailed analysis for Marathon, IA