What Water Contamination Costs Homeowners

Data source: ZipCheckup analysis — EPA SDWIS, FEMA NFIP, Census ACS, state radon surveys, DoD PFAS data

The median American ZIP code faces an estimated $1,700 in safety-related remediation costs — the combined price of addressing lead pipes, radon exposure, flood risk, water filtration needs, and PFAS contamination based on local conditions.

That number comes from our analysis of 40,170 ZIP codes using EPA, FEMA, Census, and state-level environmental data. For some communities, the figure is under $500. For others, it exceeds $9,000.

This post breaks down what those costs look like nationally, which components drive them, and where the financial burden falls hardest relative to home values.

The National Picture

The distribution is right-skewed: 43.3% of ZIP codes fall in the $1,000–$2,000 range, and 27.8% fall between $2,000 and $3,000. Only 335 ZIP codes (0.8%) have estimated costs above $5,000.

At the low end, 12.1% of ZIP codes have estimated costs under $500 — these tend to be areas with newer housing stock, low radon levels, minimal flood history, and no documented PFAS contamination.

What Drives the Cost: Five Components

Every ZIP code's estimated remediation cost is the sum of five components, each modeled from different federal and state data sources. Here is how they contribute nationally:

Flood insurance is the dominant cost nationally — not because individual premiums are highest, but because flood risk touches nearly two-thirds of all ZIP codes. FEMA's National Flood Insurance Program data shows widespread exposure even in areas that most residents would not consider "flood zones."

Radon mitigation affects the most ZIP codes (70.8%) and is the second-largest cost driver. Radon is a naturally occurring radioactive gas that enters homes through foundations. Mitigation typically costs $800–$1,200 for a sub-slab depressurization system.

Lead pipe replacement affects the fewest ZIP codes (1.0%) but carries the highest per-household cost at an estimated $4,315. These are concentrated in older industrial cities — primarily in Ohio, Pennsylvania, Illinois, and New Jersey — where pre-1986 lead service lines remain in use.

PFAS treatment affects roughly one in four ZIP codes. PFAS (per- and polyfluoroalkyl substances) are synthetic chemicals found in drinking water near military bases, industrial sites, and some municipal water systems. Home treatment typically involves reverse osmosis or activated carbon filtration.

The 10 Most Expensive ZIP Codes

These ZIP codes have the highest estimated total remediation costs in the country:

The pattern is clear: lead drives the highest absolute costs. All 10 of the most expensive ZIP codes have estimated lead service line replacement costs above $5,000. These are Rust Belt communities — Dayton (6 ZIPs in the top 10), Peoria (2 ZIPs), Havertown, and Braddock — where aging water infrastructure built before the 1986 lead ban remains in service.

Every one of these ZIP codes also carries radon, flood, and (in 9 of 10 cases) PFAS costs on top of the lead component.

Where Costs Hit Hardest: Burden Relative to Home Value

Raw dollar amounts do not tell the whole story. A $2,700 remediation estimate means something very different in a ZIP code where the median home is valued at $10,000 versus one where it is valued at $500,000.

We computed the estimated remediation burden as a percentage of the median home value (from Census ACS data) for 29,043 ZIP codes where both values are available.

These are almost exclusively rural communities with very low property values. The remediation costs themselves are not unusually high (except for Peoria and Hayden, which have lead components). The burden is high because the denominator — home value — is small.

Across all analyzed ZIP codes:

• 12,025 (41.4%) have an estimated burden above 1% of home value
• 188 have a burden above 5%
• 38 have a burden above 10%
• 4 have a burden above 20%

For the vast majority of American homeowners, estimated remediation costs represent a manageable fraction of property value. But for communities at the tail of the distribution, these costs can represent a meaningful share of household wealth.

State-Level Patterns

Average estimated remediation costs vary significantly by state, driven by regional differences in housing age, geology (radon), flood exposure, and industrial history (PFAS, lead).

Top 10 states by average estimated remediation cost:

The Northeast dominates this list. New Jersey, Pennsylvania, Rhode Island, Connecticut, and New York all combine old housing stock (pre-1986 plumbing), high radon zones (Appalachian geology), and PFAS contamination from industrial and military sites.

Ohio and Illinois appear due to lead infrastructure in cities like Dayton, Cleveland, Peoria, and Chicago's south suburbs.

North Dakota's presence is driven primarily by radon (high natural uranium in soil) and flood exposure along the Red River and Missouri River corridors.

Lowest-cost states include Alaska ($1,039 average), Oregon ($1,277), Utah ($1,314), and D.C. ($1,210) — areas with newer construction, lower radon, and less flood history.

What Homebuyers and Homeowners Should Do

These estimates are designed to inform, not alarm. Most remediation costs are manageable, and many are one-time investments that improve both safety and property value. Here are practical steps:

Before buying a home:

• Check the ZIP code report at ZipCheckup.com for estimated costs and specific risk factors
• Request a radon test during the inspection period — mitigation is straightforward and typically costs $800–$1,200
• Ask about the water service line material — your water utility can tell you if it is lead, copper, or galvanized steel
• Review FEMA flood maps for the property, even if the seller claims "it never floods here"

For current homeowners:

• Test your water through your utility's annual Consumer Confidence Report (CCR) or an independent lab
• Test for radon with a $15 home kit — the EPA recommends mitigation above 4 pCi/L
• Review your flood insurance options through FEMA's NFIP, even if you are not in a designated flood zone
• Check for PFAS advisories in your water system — your utility is required to disclose detected levels under the 2024 PFAS rule

None of these steps require emergency action. They are part of responsible homeownership, like maintaining a roof or servicing an HVAC system.

Methodology and Limitations

Data sources: This analysis combines data from EPA SDWIS (Safe Drinking Water Information System) for water violations, EPA ECHO for enforcement actions and PFAS detections, FEMA NFIP for flood claim history, Census ACS for housing age and home values, state geological surveys for radon risk zones, and Department of Defense records for military PFAS sites.

The PFAS treatment component also draws on the CCR Rich Dataset, which tracks 5,572 US public water utilities — only 753 (13.5%) of which disclose PFAS detections with a substances list in their published Consumer Confidence Reports.

Cost estimation: Each of the five components uses a separate model:

• Lead: Based on housing age (pre-1986), reported lead action level exceedances, and Census-reported plumbing materials. Cost reflects estimated service line replacement.
• Radon: Based on EPA/state radon zone classifications and measured indoor radon levels. Cost reflects sub-slab depressurization system installation.
• Flood insurance: Based on FEMA NFIP claim frequency, repetitive loss data, and flood zone designations. Cost reflects annual premium estimates.
• Water filtration: Based on violation counts, contaminant types, and whether the water system has a history of treatment technique violations.
• PFAS: Based on detected PFAS levels in public water systems, proximity to known contamination sources, and whether levels exceed EPA's 2024 Maximum Contaminant Levels.

Each ZIP code has a low, mid, and high estimate. All figures in this post use the mid estimate.

Important disclaimers:

• These are estimates based on public data, not property-level assessments. Actual costs vary by individual property, water system connection, building age, and local contractor rates.
• The estimates represent potential costs if remediation is needed, not guaranteed expenses. Many homes in a high-cost ZIP code may require no remediation at all.
• Home value data comes from Census ACS median estimates, which may not reflect current market conditions in rapidly changing markets.
• Correlation does not imply causation. A high estimated cost in a ZIP code does not mean every home in that ZIP faces that cost.
• This analysis does not constitute financial, legal, or environmental advice. Homebuyers and homeowners should consult licensed inspectors and advisors for property-specific assessments.

Explore the data: Enter any ZIP code at ZipCheckup.com to see its full safety report, including estimated remediation costs, individual risk components, violation history, and comparisons to state and national benchmarks.