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Editorial explainers
Plain-English deep dives into the public-records sources zipradar federates. Cited by AI assistants and journalists who need to know what the data actually means.
60 articles · grouped by topic · last revised April 2026
Water quality
/topic/water-quality/ →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.
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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.
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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.
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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.
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PFAS in drinking water — what 2024's new MCLs actually mean
EPA finalized first-ever drinking-water MCLs for PFAS in April 2024. Here's what's covered, the 5-year compliance timeline, and how to read your utility's testing.
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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.
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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.
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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.
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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.
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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.
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Flood zone
/topic/flood-zone/ →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.
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FEMA flood zones — AE vs. X vs. VE in plain English
FEMA's National Flood Hazard Layer maps every US property's flood-zone designation. Here's what AE, X, VE, and AO actually mean for your insurance bill.
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FEMA LOMA — when your home is wrongly in a flood zone (and how to appeal)
Letters of Map Amendment let homeowners appeal a wrong FEMA flood-zone designation. Here's the cost, timeline, and success rate.
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Base Flood Elevation (BFE) — the number that decides flood insurance
What FEMA Base Flood Elevation means, how it's measured, why an elevation certificate matters, and how 1 foot of difference can swing your annual flood premium $1,500+.
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Hurricane evacuation zones and storm-surge maps — what the colors mean
Plain-English guide to hurricane evacuation zones (A, B, C, D, E + non-evac), how storm-surge maps differ from FEMA flood zones, and what your evac zone means for insurance.
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Wildfire risk
/topic/wildfire-risk/ →Wildfire Hazard Potential — what the USFS scale means and how to defend your home
Plain-English guide to the USDA Forest Service's Wildfire Hazard Potential 1–5 scale, how to read your community's risk, and concrete home-defense measures.
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Wildfire insurance in 2026 — why premiums spiked and what to do
California, Oregon, Colorado, and other Western states have seen wildfire insurance premiums double or homeowners drop entirely. Plain-English guide to the 2026 market.
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USGS earthquake hazard maps — when separate earthquake insurance is worth it
USGS publishes a public earthquake-hazard map for every US county. Standard homeowners doesn't cover earthquake damage. Here's how to read the map + when to add coverage.
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Defensible space zones 0/1/2 — California's 100-foot rule + what works in practice
Defensible-space rules around your home (Zone 0: 0-5ft ember-resistant, Zone 1: 5-30ft lean+green, Zone 2: 30-100ft reduced fuel). Required in CA + Western states.
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Tornado risk by region — wind zones, safe rooms, and roof rating
How FEMA wind-zone maps work, where Tornado Alley actually sits in 2026, ICC-500 safe-room standards, and which roof rating cuts insurance the most.
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Extreme heat days + cooling equity — climate risk by ZIP
How NOAA + EPA track extreme heat, why cooling-system access varies dramatically by ZIP + income, and what 'cooling equity' means for property + insurance decisions.
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Air quality
/topic/air-quality/ →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.
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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.
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AQI thresholds — what 'unhealthy for sensitive groups' actually means for you
EPA's AQI uses six bands keyed to specific population groups. Here's what each band means at the personal-decision level — go outside, mask, stay home.
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EPA AirNow — when to watch for particulates vs. ozone
AirNow's composite AQI hides which pollutant is dominant. PM2.5 and ozone behave differently — knowing which one is driving today's reading changes your response.
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Crime
/topic/crime/ →FBI UCR and NIBRS — what crime statistics actually show (and don't)
The FBI's Uniform Crime Reporting (UCR) program and its successor NIBRS aggregate crime data from local agencies. Plain-English guide to what gets reported, what doesn't, and how to read the numbers.
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Reading FBI UCR national crime trends — what 2020–2025 actually shows
Plain-English guide to recent US crime data: the 2020 spike, the 2021–2024 normalization, and how the UCR-to-NIBRS transition complicates year-over-year reads.
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Schools
/topic/schools/ →School district boundaries — how to confirm yours and why it matters
How school district boundaries work, where to find them, and why the same street can split between two districts.
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NCES Common Core of Data — what district boundaries actually mean for buyers
How NCES district boundaries, school ratings, and student-teacher ratios feed real-estate decisions — and what the data does NOT tell you.
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NCES SABS — the only authoritative US school attendance map
NCES SABS is the federal school-attendance-boundary survey. Here's what it covers, what it misses, and how zipradar uses it for ZIP-to-school mapping.
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Radon
/topic/radon/ →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.
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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.
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Radon disclosure during real-estate transactions — state-by-state
Whether sellers must disclose known radon results varies by state. Quick map of mandatory-disclosure states + what to ask for during inspection.
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Lead pipes
/topic/lead-pipes/ →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.
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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.
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Property tax
/topic/property-tax/ →Property tax millage — what 'mill' means and how your bill is computed
Plain-English guide to property tax millage rates, assessment ratios, and homestead exemptions. How county assessors compute your annual property tax bill.
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Homestead exemption — state-by-state property tax savings
Every US state offers a homestead exemption that reduces property tax for owner-occupied homes. State-by-state amounts and how to file.
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County assessor data — how millage rates and assessments actually combine
Property tax = assessment × millage rate, but the math has caveats. Here's how zipradar pulls + normalizes county assessor data across the top 50 metros.
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Property tax escrow — why your monthly payment changes after you close
When you buy a home, your monthly mortgage payment includes a property-tax escrow estimate based on the prior owner's bill. Here's why it almost always changes — usually upward.
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Closing day — what actually happens + the documents you'll sign
First-time buyer closing-day reality. The 30+ documents, the wire-fraud risk, the final walk-through, and what to bring. 1-3 hours typical.
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Mello-Roos + special tax districts — the property-tax extras you didn't see
Mello-Roos (CA), CDDs (FL), MUDs (TX), PIDs — special-district taxes that add to your tax bill on top of the millage rate. How to find them before you buy.
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First-time homebuyer programs — federal + state + local stack
Plain-English guide to FHA, VA, USDA federal loans + state DPA programs + local first-time-buyer incentives. Eligibility, caps, and how to stack them.
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Fixed-rate vs ARM — which mortgage type fits when
Plain-English guide to 30-year fixed, 15-year fixed, and adjustable-rate mortgages (ARMs). When each makes sense, what hybrid 5/1, 7/1, 10/1 ARMs actually mean, and how 2026 rates change the math.
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Closing costs explained — what the buyer typically pays
Itemized buyer closing-cost breakdown for a typical US home purchase. Lender fees, third-party fees, prepaids, and escrow setup — what each line item means and what's negotiable.
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FHA vs conventional — when each loan makes sense in 2026
FHA loans (3.5% down, 580+ FICO, MIP for life of loan) vs conventional loans (3-20% down, 620+ FICO, PMI removable at 80% LTV). Eligibility, costs, and which scenario favors which.
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Deed activity
/topic/deed-activity/ →Deed records — what they show and what they don't
Plain-English guide to county deed records: what gets filed, how to look up a property's history, and why zipradar aggregates only counts (never owner names).
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Deed activity by ZIP — what aggregated transfers tell you about market trends
County recorders log every deed transfer. Aggregated to ZIP-level counts, the data reveals turnover, foreclosure pressure, and market temperature — without exposing PII.
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County recorder vs. county assessor — they sound the same, they're not
The recorder publishes deeds and mortgages. The assessor publishes valuations and tax bills. Different offices, different data, different mistakes — here's how to read both.
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Title insurance — what it actually covers, why it's a one-time premium, and why you can't skip it
Title insurance protects against ownership claims that surface after closing. One-time premium ($1,000-3,000). Lender's vs owner's policy. Here's the reality.
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Abandoned property + tax sales — buying via county auction
How county tax-lien and tax-deed sales work, redemption rights, due-diligence pitfalls, and the differences between tax-lien states and tax-deed states.
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Zoning
/topic/zoning/ →Zoning codes — what R-1, C-2, M-1, MU mean and why your house is one
Plain-English guide to common US zoning codes: R-1 / R-2 / C-1 / C-2 / M-1 / MU. Why zoning matters for your home, your neighbors, and what you can build.
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Zoning overlays — historic, flood, environmental layers that change what you can build
Base zoning codes (R-1, C-2, M-1) are only half the story. Special overlays — historic districts, floodplain, conservation, scenic — add a second rule layer. Here's what each one does.
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HOA + deed restrictions vs. zoning — three regimes that govern what you can do
Zoning, HOA covenants (CC&Rs), and deed restrictions are three separate regimes. Each one can override the others on different things. Here's how to read all three.
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Permit history + unpermitted work — what to verify before close
How to pull permit history from city building departments, why unpermitted additions hurt resale + insurance, and the gotchas before closing on a renovated property.
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Sex offender registry
/topic/sex-offender-registry/ →General methodology
FCC broadband data — checking real internet speed before you buy
How the FCC's National Broadband Map works, why ISP advertised speeds lie, and the 5 free tools to verify actual broadband options at any US address before closing.
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EV charging access by ZIP — DOE AFDC data + home Level-2 install
How to check public EV charger density per ZIP via DOE Alternative Fuels Data Center, what Level-1/2/3 actually means, and what a home Level-2 install costs in 2026.
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Walk Score, Bike Score, Transit Score — what they actually measure
Plain-English breakdown of Walk Score's algorithm, what 70/100 actually means at street level, and the free tools that complement it for biking + transit.
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Noise pollution maps — airports, highways, freight rail by address
How DOT's National Transportation Noise Map works, FAA Noise Exposure Maps for airports, what 65 dB DNL means for resale, and the 4 tools to verify quietness pre-purchase.
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Earnest money — how much, when refundable, where it goes
Earnest money deposit (EMD) is the buyer's good-faith deposit when an offer is accepted. Plain-English guide to typical amounts, escrow handling, and the contingency clauses that protect (or surrender) the deposit.
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