Glossary

SDWIS (Safe Drinking Water Information System)

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

Operated by the EPA, SDWIS aggregates compliance data reported by states under the Safe Drinking Water Act. Each community water system (CWS) appears with a unique PWSID identifier, its served population, and its violation history.

Updated quarterly. zipradar federates SDWIS at /topic/water-quality/ — showing the dominant CWS per ZIP, last 3 years of violations, and lead-copper results.

LCRR (Lead and Copper Rule Revisions)

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

The Lead and Copper Rule Revisions require every water system to publish a service-line inventory by October 2024 identifying lead, galvanized-requiring-replacement, non-lead, and unknown lines.

The rule lowers the lead trigger level to 10 µg/L (down from 15 µg/L action level under the original rule) and mandates replacement of identified lead lines within 10 years.

PWSID (Public Water System ID)

Federal 9-character identifier assigned to every regulated US community water system (state code + 7-digit number).

Every public water system carries a PWSID. zipradar uses PWSID as the join key between SDWIS violation records and the geographic ZIPs each system serves.

Tier 1 violation (acute health-based)

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

EPA classifies violations into Tier 1 (acute health, 24-hour public notice), Tier 2 (chronic health, 30-day notice), and Tier 3 (monitoring/reporting, annual notice). Tier 1 events appear with red flags on zipradar.

Service line inventory (SLI)

Mandatory LCRR catalog identifying every water service line as lead, galvanized-requiring-replacement, non-lead, or unknown.

Required for every US public water system as of October 2024. Updated annually. Used by lenders + insurers to assess remediation cost on home transactions.

FIRM (Flood Insurance Rate Map)

Official FEMA map showing flood-zone designations + base flood elevations for the 1% annual-chance flood for every US property.

FIRMs are the binding regulatory documents for NFIP flood insurance + lender flood-determination requirements. Updated by FEMA via map-revision projects, often in 5-10 year cycles.

BFE (Base Flood Elevation)

Elevation in feet above sea level that water reaches in a 1% annual-chance flood — the number that drives NFIP premium rating.

BFE applies in A, AE, AH, AO, V, VE flood zones. Lowest-floor elevation relative to BFE determines premium tier under NFIP Risk Rating 2.0.

LOMA (Letter of Map Amendment)

Official FEMA decision removing a structure from a Special Flood Hazard Area when natural ground elevation is at or above BFE.

Free to apply. Issued by FEMA after submission of an Elevation Certificate showing ground elevation. Successful LOMA = no mandatory NFIP coverage requirement on a federally-backed mortgage.

NFHL (National Flood Hazard Layer)

FEMA's authoritative GIS dataset combining all current FIRMs into a single nationwide flood-hazard layer.

Updated continuously. NFHL is the primary source zipradar federates for /topic/flood-zone/.

WHP (Wildfire Hazard Potential)

USDA Forest Service 5-step landscape-level wildfire-hazard score — Class 1 (very low) through Class 5 (very high).

Updated annually. Reflects landscape conditions (fuel load, climate, terrain), NOT property-specific factors like defensible space or roof material.

Defensible space

Maintained zone (typically 100 feet) around a structure where fuels are reduced to slow wildfire spread.

California PRC §4291 + similar laws in OR, CO, WA require Zone 0 (0-5 ft, hard surfaces only), Zone 1 (5-30 ft, lean clean green), Zone 2 (30-100 ft, reduced fuel).

ICC-500 (storm shelter standard)

International Code Council standard for tornado + hurricane safe rooms — wind speeds, debris loading, anchorage.

Pairs with FEMA P-361 design guidance. Required for FEMA Hazard Mitigation Grant Program rebates on home shelters in Plains states.

AQI (Air Quality Index)

EPA's 0-500 scale converting pollutant concentrations into a single index — Good (0-50) to Hazardous (301+).

Calculated for 5 pollutants: ozone, PM2.5, PM10, CO, NO2, SO2. The reported AQI is the maximum across pollutants. Live + historical via EPA AirNow.

PM2.5 (fine particulate matter)

Airborne particles 2.5 microns or smaller — small enough to enter lungs + bloodstream; primary wildfire-smoke health driver.

Sources: combustion (cars, power plants), wildfires, dust. EPA NAAQS 24-hr standard: 35 µg/m³ (revised 9 µg/m³ annual mean in 2024 update).

Ground-level ozone (O₃)

Secondary pollutant formed when nitrogen oxides + volatile organics react in sunlight — peaks summer afternoons.

Distinct from stratospheric ozone (good ozone). Ground-level ozone triggers asthma + reduced lung function. EPA standard: 70 ppb 8-hour.

UCR (Uniform Crime Reporting)

FBI program collecting standardized crime statistics from local agencies — historically Part I + II offenses; now NIBRS-based.

Originated 1930. As of 2021, UCR transitioned to NIBRS as the data backbone. Crime Data Explorer surfaces normalized per-capita rates.

NIBRS (National Incident-Based Reporting System)

Incident-level FBI crime database — 52 offense categories, victim/offender demographics, multi-offense per incident.

Replaces summary UCR. Provides far richer detail but adoption is uneven across local agencies; some report incomplete years.

CCD (Common Core of Data)

NCES annual census of every public elementary + secondary school in the US — enrollment, demographics, finance, locale.

Released annually. zipradar federates CCD at /topic/schools/ for school-by-ZIP coverage with locale + enrollment + Title I status.

SABS (School Attendance Boundary Survey)

NCES geographic dataset mapping the catchment boundary of every public elementary, middle, and high school in the US.

Used to determine which school a given residential address is zoned for. Updated biennially.

Title I (Elementary and Secondary Education Act)

Federal program providing supplemental funding to schools with high concentrations of low-income students.

Title I status appears in CCD records. Used as a proxy signal for student-population economic profile when zipradar surfaces school metadata.

EPA Radon Zone 1

EPA's highest-priority radon zone — counties with predicted average indoor radon ≥4 pCi/L (the action level).

Mapped in 1993 baseline; updated by states with newer surveys. Zone 1 counties span CO, IA, KS, KY, MN, MT, ND, NE, OH, PA, SD, WY + many others.

pCi/L (picocuries per liter)

Standard US unit for indoor radon concentration. EPA action level: 4 pCi/L; mitigation considered: 2-4 pCi/L.

Long-term test (90+ days) is the recommended method for real-estate decisions. Short-term tests (2-7 days) are screening only.

Millage rate (mill levy)

Property tax rate expressed as dollars of tax per $1,000 of assessed value. 1 mill = $1 per $1,000.

Total property tax = millage × (assessed value / 1,000). Set by overlapping taxing districts: school, county, municipal, special-service.

Homestead exemption

State-law tax break reducing property tax on a primary residence — varies wildly state-by-state.

Texas: $100k school-tax exemption. Florida: $50k + Save Our Homes 3% cap. California: Prop 13 acquisition-value caps. Most other states: $5-25k modest reductions.

Mello-Roos Community Facilities District

California special tax district funding new infrastructure (schools, roads) via additional property-tax assessment for 20-40 years.

Common in newer California subdivisions (post-1982). Adds $1,000-$5,000+ to annual property tax bills. Disclosed at sale via Mello-Roos statement.

Deed of trust

3-party security instrument (borrower, lender, trustee) used in lieu of mortgages in 30+ US states.

Trustee holds title until loan is paid; non-judicial foreclosure path. zipradar surfaces deed-recording activity at ZIP-rollup level (never individual owner names).

Title insurance

One-time-premium policy protecting against undiscovered defects in property title — owner's policy + lender's policy distinct.

Owner's policy: optional, protects equity, lasts as long as you own. Lender's policy: required by mortgage, covers loan balance only.

R1 zoning (single-family residential)

Most-restrictive residential zoning — single-family detached only, minimum lot size, minimum setbacks.

Variants: R1-6, R1-8, R1-10 etc. (number = minimum lot size in thousands of sq ft). Modern reform: many cities now permit ADUs in R1 by right.

ADU (Accessory Dwelling Unit)

Secondary independent dwelling on a single-family parcel — granny flat, in-law unit, garage conversion, detached cottage.

California SB 9 + AB 68 + similar Oregon, Washington, NY laws now mandate by-right ADU permits in most R1 zoning — fundamentally altering single-family character.

HOA deed restriction (CC&R)

Private covenant in subdivision deeds restricting use, appearance, or occupancy — often stricter than public zoning.

Conditions, Covenants, and Restrictions (CC&Rs) bind every owner. Run with the land. Can override more permissive zoning (e.g., HOA bans ADU even where city allows).

NSOPW (National Sex Offender Public Website)

DOJ-operated portal aggregating state + tribal + territorial sex-offender registries into a single search interface.

zipradar deep-links to NSOPW search results by ZIP — never caches personal records. Users complete searches on the official DOJ site.

YMYL (Your Money or Your Life)

Google's content category for pages where misinformation could harm a user's finances, health, or safety — held to higher quality standards.

Pages on real estate, health, and safety qualify. zipradar publishes only public-records data with primary-source citations + visible 'Last verified' dates per Google E-E-A-T guidance.

E-E-A-T (Experience, Expertise, Authoritativeness, Trust)

Google's quality framework for content evaluation — Experience added to EAT in December 2022.

Operationalized via author bylines, methodology pages, primary-source citations, contact information, transparent dates of last review.

IndexNow

Open protocol (Microsoft + Yandex) letting websites notify search engines of URL changes immediately, bypassing crawl-delay.

Supported by Bing, Yandex, Seznam, DuckDuckGo. zipradar pings IndexNow on every deploy via scripts/indexnow-ping.mjs.

Elevation Certificate (EC)

FEMA-mandated survey documenting a building's lowest-floor elevation relative to BFE — required for lowest NFIP premium tier.

Completed by a state-licensed land surveyor. Cost: $400-$900. Required by lenders for properties in A, AE, AH, V, VE flood zones to qualify for accurate Risk Rating 2.0 pricing.

NFIP (National Flood Insurance Program)

FEMA-administered federal flood-insurance program — only widely-available source of residential flood coverage in the US.

Standard homeowners policies exclude flood. NFIP fills the gap for participating communities (those that adopt FEMA floodplain-management standards). Coverage cap: $250k structure + $100k contents.

Risk Rating 2.0 (rolled out 2021-2023) replaced legacy zone-only pricing with parcel-level granular pricing.

WUI (Wildland-Urban Interface)

The geographic zone where homes meet undeveloped wildland vegetation — highest wildfire-property-loss risk.

Defined by USGS + USFS. Roughly 1/3 of US homes (44 million) sit in WUI. WUI residents face the brunt of recent California, Oregon, Colorado catastrophic-fire losses.

Insurance carriers increasingly use WUI classification + parcel-level WHP for underwriting decisions.

FRAP (CAL FIRE Fire and Resource Assessment Program)

California's authoritative wildfire-hazard-zone mapping program — feeds Fire Hazard Severity Zone (FHSZ) classifications.

FHSZ tiers: Moderate, High, Very High. Drives California PRC §4291 defensible-space requirements + insurance carrier underwriting.

NAEP (National Assessment of Educational Progress)

Federally-administered student assessment — the 'Nation's Report Card' — math + reading scores by grade + state.

Administered every 2 years to 4th + 8th graders nationally + selected high-schoolers. Different from state-administered tests; used for cross-state comparison.

Title III (English language acquisition)

ESEA federal funding stream for English-language-learner programs in K-12 schools.

Title III status appears in CCD records. Used as a signal of school's English-learner population concentration.

Easement

Recorded right of one party to use another's land for a specific purpose — utility, access, conservation, etc.

Common types: utility easements (power, water, sewer), access easements (driveway/road), conservation easements (preserve open space, often tax-deductible). Disclosed at title search.

Encumbrance

Any claim or restriction on a property's title that may diminish its value — liens, easements, deed restrictions, encroachments.

Title insurance protects against undisclosed encumbrances. Buyer review of preliminary title report (PTR) before close is critical.

Lien

Legal claim against property to secure debt — mortgage liens, mechanic's liens, tax liens, judgment liens.

Liens recorded in county records. Mortgage lien is the most common; mechanic's liens (unpaid contractors) often surprise sellers at closing. Senior liens paid first at sale.

As-of-right (zoning)

Land use permitted by zoning code without requiring a discretionary review, variance, or special exception.

If a use is as-of-right, the local building department issues a permit on application. Non-as-of-right uses require zoning-board review (variance, special permit, conditional use).

Variance (zoning)

Discretionary zoning-board approval relaxing a specific rule (setback, height, lot coverage) for a specific parcel.

Variance applications require demonstrating 'unnecessary hardship' or unique parcel conditions. Public hearing usually required. Granted variances are recorded against the deed.

Setback

Minimum distance a building must sit from a lot line — front, side, rear setbacks defined per zoning district.

Common R1 setbacks: 25 ft front, 5-10 ft side, 20 ft rear. Encroachments require variance. Setbacks shape neighborhood character + light/air access.

FHFA conforming loan limit

Annual maximum mortgage-loan amount eligible for purchase by Fannie Mae or Freddie Mac — varies by county.

2025 baseline: ~$766k single-family; high-cost-area limit ~$1.15M. Loans above are 'jumbo' — different rates + underwriting. The county limit influences home-price ceiling.

Post-FIRM (post-Flood-Insurance-Rate-Map)

Buildings constructed AFTER the community's first FIRM was issued — built to floodplain-compliant standards by code.

Post-FIRM properties get NFIP rates based on actual elevation difference from BFE. Pre-FIRM properties (older buildings) often get grandfathered rates that may be cheaper than flat-elevation pricing.

BDC (Broadband Data Collection)

FCC's 2022-onward replacement for Form 477 — collects ISP coverage data at the location level instead of census-block level.

Output is the National Broadband Map at broadbandmap.fcc.gov. Updated semi-annually. Public can challenge ISP-reported coverage via the BDC challenge process.

AFDC (Alternative Fuels Data Center)

DOE-operated authoritative directory of every public EV charger + alternative fuel station in the US.

Searchable map at afdc.energy.gov/stations. Filterable by connector type (J1772/CCS/CHAdeMO/Tesla NACS), charging level (L1/L2/DCFC), network, and access (24/7 vs limited).

Updated weekly via partnership with PlugShare + station operators.

Level 2 EV charging

240V EV charging — ~25-40 miles range/hour. Standard for home installation + most public chargers (workplaces, retail).

Hardware: ~$400-$900. Electrician install: ~$400-$2,500. Federal IRA Section 30C tax credit covers 30% up to $1,000 through 2032.

DCFC (DC Fast Charging) / Level 3

50-350 kW EV charging — 10-80% charge in 18-40 minutes. Highway corridors + paid stations only.

Tesla Supercharger, Electrify America, EVgo, ChargePoint Express are major networks. Connector: CCS for most non-Tesla; Tesla NACS becoming standard in 2026.

Walk Score

0-100 walkability index from Walk Score (Redfin) — measures distance to amenities + intersection density + block length.

90-100 Walker's Paradise. 70-89 Very Walkable. 50-69 Somewhat Walkable. 25-49 Car-Dependent. 0-24 Car-Dependent.

Doesn't account for hills, weather, sidewalk quality, or safety. Verify with on-foot visit.

Transit Score

0-100 index measuring distance to + frequency of public-transit lines (bus, light rail, heavy rail, ferry).

Frequency matters more than mere presence. City averages: NYC 84, SF 80, Boston 74, Chicago 65, DC 71, Seattle 60, LA 53.

NTNM (National Transportation Noise Map)

DOT/BTS map combining highway + rail + aviation noise into a 0-90+ dB color-coded nationwide layer.

Updated annually. Color thresholds: <50 dB residential-acceptable, 50-60 dB suburban-typical, 65-75 dB high (highway-adjacent), 75+ dB unacceptable for residential.

DNL (Day-Night Average Sound Level)

FAA + EPA standard for cumulative airport noise — 24-hour average dB with 10 dB nighttime penalty (10pm-7am weighted higher).

65 dB DNL is the FAA threshold for 'noise-impacted' residential property under Part 150.

NEM (Noise Exposure Map)

FAA-required Part 150 map showing 65 dB DNL contour around an airport — properties inside are formally noise-impacted.

Resale impact: properties inside 65 dB DNL contour sell 8-15% below comparable properties outside the contour.

Starlink (rural broadband fallback)

SpaceX low-earth-orbit satellite internet — 50-200+ Mbps with ~30-50ms latency, available in most US locations excluding heavy obstructions.

Hardware: ~$400-$600 dish. Service: ~$120/mo standard residential. Most-cited fallback for rural addresses with no fiber/cable/fixed-wireless option.

FEMA Map Service Center (MSC)

Authoritative FEMA portal for ordering parcel-level FIRM panels + flood-determination certificates + LOMA applications.

Free FIRMette downloads available. Letter of Map Amendment (LOMA) applications + Elevation Certificate uploads happen here.

IRA Section 30C (Alternative Fuel Refueling Property Credit)

Federal tax credit covering 30% of EV charger install cost (up to $1,000 residential) through 2032 in eligible census tracts.

Eligible tracts: low-income communities + non-urban areas (covers most US ZIPs not in dense metropolitan cores). Residential cap: $1,000. Commercial cap: $100,000.

CCA (Community Choice Aggregation)

Community-level electricity-sourcing program where local government negotiates renewable supply on behalf of residents.

Common in CA, NY, MA, IL, OH, NJ. Defaults customers into the program; opt-out preserves utility-default service. Often offers cleaner-mix or lower-cost rates than incumbent utility.

DOI (Department of Interior — public lands)

Federal department managing 480 million acres of public land via BLM, NPS, USFWS, BIA. Adjacent property values affected by access + grazing rights.

Properties bordering BLM land have public-access easements. National Park / monument adjacencies often boost values 10-25%. Tribal-trust land complications require disclosure.

ALTA Survey

Standardized boundary survey accepted by lenders + title insurers nationally — boundary lines, encroachments, utilities, easements per ALTA/NSPS table A.

Costs $400-$2,500 depending on parcel size + complexity. Required for commercial transactions; recommended for residential when title questions exist (boundary disputes, easement claims).

Cap rate (capitalization rate)

Investment-property valuation metric: net operating income ÷ purchase price. Lower cap rate = higher price relative to income.

Typical residential rentals: 4-8%. Class-A multifamily: 4-5%. Tertiary markets: 7-10%. Used to compare property investment yields independent of financing.

1031 exchange (like-kind exchange)

IRS provision allowing deferral of capital-gains tax when investment property is exchanged for another investment property within 180 days.

Strict rules: identify replacement within 45 days, close within 180 days, qualified intermediary required. Primary residences NOT eligible (separate Section 121 exclusion applies).

Section 121 (capital gains exclusion)

IRS exclusion: $250k single / $500k married of capital gains on sale of primary residence if owned + occupied 2 of last 5 years.

Doesn't roll over — use it or pay. Limited to once every 2 years. Reduces by partial-period if not full 2 years lived.

Schedule C (NFIP add-on coverage)

NFIP optional policy adding contents, basement, or building-code-upgrade coverage on top of standard policy.

Standard NFIP: $250k structure + $100k contents. Schedule C ICC adds up to $30k for code-required elevation/demolition after declared flood event. Often unused; ask for it.

Transformer capacity (electrical service)

Local utility's incoming transformer max load — limits how much electrical service a property can support without upgrade.

Old subdivisions often have 60-100 amp service; modern requirements (EV charging + heat pump + induction) need 200-400 amp + new transformer. Utility upgrades cost $5,000-$25,000+ if transformer needs replacement.

Septic system (on-site wastewater)

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

Lifespan: 25-40 years. Replacement: $5,000-$25,000+ depending on soil conditions + system size. Inspection mandatory at sale in many states. Failure to maintain = environmental violation + costly remediation.

Perc test (percolation test)

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

Measures rate water drains through soil. Failed perc = no septic = unbuildable in many counties. Cost: $200-$1,500. Always done before purchase of undeveloped lots.

ADA compliance (Americans with Disabilities Act)

Federal accessibility requirements for commercial properties + multi-family rentals — ramps, doorways, parking, restrooms.

Title III applies to public accommodations + commercial facilities. Multi-family rentals built post-1991 = FHAA accessibility requirements. Title II = state/local government buildings.

HVAC zoning

Multi-zone climate control allowing different temperatures in different parts of the home — 2-zone, 3-zone, 4-zone systems common.

Reduces energy cost 20-40% vs single-zone. Adds $1,500-$5,000 to install. Zone count is a real-estate listing claim worth verifying — false zones (one thermostat, multiple registers) common.