Water quality by ZIP code

SDWIS (Safe Drinking Water Information System)

EPA's federal database of every community water system, its violations, lead-and-copper sampling, and treatment data.

LCRR (Lead and Copper Rule Revisions)

EPA's 2024 update tightening lead-pipe inventories, sampling procedures, and trigger thresholds for action by water systems.

Tier 1 violation (acute health-based)

Most-serious water-quality violation requiring 24-hour public notice — coliform/E. coli, nitrate exceedance, chlorine dioxide exceedance.

Septic system (on-site wastewater)

Self-contained wastewater treatment for properties without public sewer — typically tank + leach field + soil percolation.

Perc test (percolation test)

Soil-permeability test required by health department before installing septic system or building on undeveloped land.

Vapor intrusion (VI)

Migration of volatile organic compounds (VOCs) from contaminated groundwater or soil into the indoor air of an overlying building — a recognized exposure pathway at Superfund + brownfield sites.

Flood zones explained — what AE, X, and VE actually mean

Plain-English guide to FEMA flood-zone codes (A, AE, AH, V, VE, X, X-shaded). What the 1% and 0.2% annual-chance zones mean for your property and your insurance.

EPA Radon Zones — what 1, 2, and 3 mean and when you should test

EPA classifies every US county into Zone 1 (high), Zone 2 (moderate), or Zone 3 (low) for radon. Plain-English guide to the classifications and at-home testing.

EPA AQI categories explained — what 0–50 Good through 301–500 Hazardous mean

Plain-English guide to the six EPA Air Quality Index categories: 0–50 Good, 51–100 Moderate, 101–150 Unhealthy for Sensitive Groups, 151–200 Unhealthy, 201–300 Very Unhealthy, 301–500 Hazardous — what each level means and who is at risk.

Lead and Copper Rule 2024 — the federal lead-pipe inventory mandate

The 2024 Lead and Copper Rule Revisions (LCRR) require every US community water system to inventory and report lead service lines. Plain-English guide.

AQI explained — what 50, 100, 150 actually mean for your lungs

Plain-English guide to the EPA Air Quality Index (AQI) and the 6 categories from Good to Hazardous. When to take precautions and which pollutants matter.

EPA SDWIS — how to read drinking-water violations and what they actually mean

Plain-English guide to EPA SDWIS drinking-water violations: health-based vs. monitoring vs. reporting violations, MCLs, and what triggers a public notice.

AirNow + wildfire smoke — when AQI is a real-time tool

How EPA AirNow handles real-time wildfire smoke, what the colors mean during fire season, and where AirNow leaves gaps you should know about.

Radon and real estate — what disclosure laws and home tests actually require

What home sellers must disclose about radon by state, when home tests are required, and how to interpret radon-mitigation systems if a home you're buying has one.

EPA SDWIS — reading drinking-water violations without panicking

EPA's drinking-water database flags violations across every public water system. Here's how to read what's in your ZIP — and what 'violation' actually means.

Buying a house — the 12-dimension data checklist before you sign

Twelve federated public-records dimensions every US homebuyer should check before closing. Synthesized from EPA, FEMA, FBI, NCES, county assessors + recorders.

Private well water — what to test when EPA SDWIS doesn't cover you

EPA SDWIS only covers public water systems. Private wells (~13% of US homes) are the homeowner's responsibility. Here's what to test, how often, and what each test costs.

PFAS in Your Drinking Water: the 2024 EPA Limits, Explained

What the EPA's first-ever PFAS drinking-water limits (finalized April 2024) actually cover, the compliance timeline, and how to read your utility's test results.

Lead in paint vs. lead in pipes — same metal, different exposure

Lead service lines (LCRR) and lead-based paint (Title X) are governed by separate regulatory regimes. Here's how each one matters when buying an older home.

EPA Superfund + Brownfields — what 'contaminated site nearby' actually means

EPA's National Priorities List (Superfund) flags the most contaminated sites in the US. Brownfields tracks lower-tier abandoned-industrial sites. Here's how to read both.

Data staleness — when to re-check zipradar before making a decision

Federal data refreshes on different cadences. Here's when zipradar's snapshot is fresh enough for your decision and when you need to verify with the primary source.

Septic systems — what they fail on, what tests cost, when they're a deal-breaker

About 21% of US homes use a septic system. They fail in patterns. Here's the inspection cost, common failures, and when a failed septic is reason to walk from a deal.

Groundwater vs municipal water — which does your address have, and how to tell

About 13% of US households are on private wells. Here's how to tell which water source serves your address — and what each means for testing, cost, and quality.

Drought, water rights, and private wells — when your tap runs dry

How drought levels affect well users in the West, water-rights doctrine (riparian vs. prior-appropriation), and what to verify before buying a property on private well in a drought-prone state.

Phase 1 Environmental Site Assessment — when you need one, what it costs, what it finds

A Phase 1 ESA is the standard environmental due-diligence for commercial real estate + some residential. Plain-English guide to when one is required, what it covers, and the $1,500-5,000 cost.

Well + septic inspection — exactly what to demand before closing on a rural home

Rural + exurban homes on private well + septic require specialized inspections beyond standard home inspection. Plain-English buyer checklist + cost estimates.