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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.
69 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 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.
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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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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.
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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.
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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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Homeowners insurance by peril — what's covered, excluded, and surprise gaps in 2026
Standard HO-3 policies cover fire, theft, and most weather — but exclude flood, earthquake, sinkhole, and back-of-policy surprises. Plain-English guide to peril-by-peril coverage.
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Hurricane + wind-rated construction — what 'fortified' actually means and which features cut insurance 20-50%
FORTIFIED Home + Miami-Dade approval + impact-rated windows reduce hurricane risk + insurance premiums 20-50% in coastal states. Plain-English buyer guide with cost-benefit.
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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/ →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.
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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/ →How to Find Your School District by Address (and Confirm the Boundary)
Find which school district any address belongs to, confirm the exact boundary, and see why one street can split between two districts. A plain how-to.
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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 Mortgage Payment Jumps After You Buy
Your mortgage's property-tax escrow is set from the prior owner's bill, so it almost always rises after you close. Here's why, and how to prepare for the adjustment.
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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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Property tax appeal — how to win one, when it's worth your time, and what assessors won't tell you
60-70% of property-tax appeals succeed when properly documented. Plain-English guide to the appeal process, evidence that wins, and when the $1-2k consultant fee pays off.
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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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Buying a foreclosure or short sale — what's different, what's risky, and what you need to verify
Foreclosures + short sales can save 5-30% but bring inspection access limits, title defects, deferred maintenance, and 3-9 month closing delays. Plain-English buyer guide.
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Easements + rights of way — how the legal markings on your survey actually affect what you can build
Utility easements, drainage easements, ingress/egress, and conservation easements each restrict different building rights on your parcel. Plain-English buyer guide with survey-reading tips.
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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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Home warranty vs builder warranty vs inspection — what each one actually covers (and which to pay for)
Home warranty, builder warranty, and home inspection are three different things buyers conflate. Plain-English guide to what each covers, costs, and how to use them.
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