REST API · v1

Water quality intelligence
for every US address.

One API call. Municipal systems, private wells, PFAS, lead, 30+ contaminants. A–F grades your users actually understand.

See example responses ↓

Send an address

GET /api/v1/water?address=123 Main St, Denver CO

Any US address, lat/lng coordinates, or water system ID.

Get a grade

Overall A–F water quality grade plus per-contaminant breakdown. Municipal or private well — the API figures out which.

Display it

Letter grades, risk flags, contaminant details — everything you need for a listing page, disclosure report, or risk dashboard.

What you get in every response

PFAS detection

Per-compound PFAS detection and MCL exceedance flags from EPA’s fifth Unregulated Contaminant Monitoring Rule.

Source: EPA UCMR5 · Federal monitoring data

Lead risk tier

Service line material inventory data — known lead lines, unknown lines, and worst-case percentages.

Source: EPA LCRR · Federal inventory data

Violation history

Ten-year health violation count, open violations, and trend direction from EPA compliance records.

Source: EPA SDWIS · Federal compliance data

CCR contaminant data

Utility-reported contaminant concentrations extracted and normalized from Consumer Confidence Reports. Coverage: ~49% of US population. Actively expanding.

Source: Utility CCRs · Preliminary — expanding & refining

Well chemistry

Nearby monitoring well results and USGS modeled risk for PFAS, arsenic, and nitrate at any US coordinate.

Source: USGS WQP, TWDB · Federal & state monitoring data

Address resolution

Any US address geocoded and matched to the correct water system or classified as a private well area.

Real API responses

These are actual responses from the WaterScore API. Not mock data.

GET/api/v1/water?pwsid=CA1910067

Overall Grade

Water Type

municipal

PFAS

CCR Grade

17 contaminants graded

Worst Finding

Bromate

76% of federal MCL

Full municipal response

{
  "request_id": "a3f2d1b0-7c4e-4abc-8def-112233445566",
  "pwsid": "CA1910067",
  "system_name": "LOS ANGELES-CITY, DEPT. OF WATER & POWER",
  "water_type": "municipal",
  "state": "CA",
  "population_served": 4041284,
  "service_area": "LOS ANGELES",
  "overall_grade": "B",
  "grades": {
    "pfas": {
      "grade": "A",
      "detected": false,
      "detected_compounds": [],
      "above_mcl": false
    },
    "lead": {
      "grade": "A",
  ...
}

API Reference

Full interactive docs →

Request Parameters

Field	Type	Description
`address`	string	Any US street address. Geocoded automatically.
`lat, lng`	number	Coordinates. Use instead of address for precision.
`pwsid`	string	9-character EPA water system ID. Fastest lookup.

Priority: pwsid → lat/lng → address. At least one required.

Top-Level Response

Field	Type	Description
`request_id`	string	Unique ID for this request
`pwsid`	string	EPA water system ID (municipal only)
`system_name`	string	Water system name (municipal only)
`water_type`	"municipal" \| "well"	Whether address is on public water or a private well
`overall_grade`	A–F	Composite water quality grade
`data_sources`	string[]	Which data sources contributed (SDWIS, UCMR5, CCR, WQP)
`data_confidence`	object	Per-source data maturity: "verified" (federal/state data) or "preliminary" (WaterScore-extracted, expanding coverage)

Grades Object (Municipal)

Field	Type	Description
`grades.pfas.grade`	A–F \| N/T	PFAS contamination grade. N/T = not tested under UCMR5.
`grades.pfas.detected`	boolean	Whether any PFAS compounds were detected
`grades.pfas.above_mcl`	boolean	Whether any PFAS exceed federal limits
`grades.lead.grade`	A–D \| ?	Lead risk based on service line inventory data
`grades.lead.risk_tier`	string	none, low, medium, high, unknown_high, no_data
`grades.violations.grade`	A–F	Based on EPA compliance history (10-year window)
`grades.violations.has_open_violations`	boolean	Currently unresolved health violations
`grades.violations.trend`	string	improving, stable, or worsening
`grades.chromium6.grade`	A \| C \| F	Hexavalent chromium (Erin Brockovich contaminant)
`grades.lithium.grade`	A \| B \| C	Naturally occurring lithium levels

CCR Object (Municipal, when available)

Field	Type	Description
`ccr.available`	boolean	Whether CCR data exists for this system
`ccr.report_year`	number	Year of the Consumer Confidence Report
`ccr.overall_grade`	A–F \| null	Grade based on worst federal primary standard contaminant
`ccr.contaminants`	array	Per-contaminant breakdown
`ccr.contaminants[].name`	string	Contaminant name
`ccr.contaminants[].grade`	A–F	Individual contaminant grade
`ccr.contaminants[].value`	number	Detected level
`ccr.contaminants[].mcl`	number	Federal limit (MCL, action level, or secondary standard)
`ccr.contaminants[].pct_of_mcl`	number	Detected level as fraction of limit (1.0 = at limit)
`ccr.contaminants[].limit_type`	string	federal, action_level, secondary, or who

Well Object (Private well)

Field	Type	Description
`nearby_wells.count_in_radius`	number	Monitored wells within search radius
`nearby_wells.radius_miles`	number	Search radius used
`nearby_wells.grades`	object	Per-contaminant grades from nearby monitoring wells
`modeled_risk`	object	USGS statistical model predictions (pfas, arsenic, nitrate)
`modeled_risk.*.grade`	A–F	Risk grade from model probability
`modeled_risk.*.probability`	number	Probability of exceedance (0–1)

Grade Scale

Field	Type	Description
`A`	Excellent	Well within limits (<10% of MCL) or not detected
`B`	Good	Detected at low levels (10–30% of MCL)
`C`	Moderate	Moderate levels (30–70% of MCL) or informational finding
`D`	Concern	Approaching limits (70–100% of MCL)
`F`	Failing	Above federal limits
`N/T`	Not Tested	PFAS only — system not included in EPA monitoring
`?`	Unknown	Lead only — service line inventory data unavailable

Water quality is a material risk factor — and nobody’s data covers it.

PFAS contamination depresses property values. Lead service line replacement costs fall on homeowners. Private well contamination kills rural land deals. Proptech platforms, lenders, and environmental consultants integrate flood, wildfire, and air quality data — but drinking water quality has been a blind spot. The data exists — it’s buried across 48,000 individual utility reports, state databases, and federal monitoring programs. Nobody had stitched it together.

WaterScore extracts, normalizes, and grades that data so you don’t have to.

Built for proptech

Property listings

Add a water quality grade badge to every listing. Flag properties with PFAS detections or lead risk before your buyers ask.

Mortgage & risk

Screen addresses for water quality risk at origination. 48,000+ municipal systems and private well coverage nationwide.

Relocation tools

Help movers compare water quality across cities. One API call returns everything — no hydrogeology degree required.

48,000+

water systems graded

~49.4%

US population with CCR data

30+

contaminants tracked

Nationwide

private well chemistry for any coordinate

Need the full dataset?

For platforms that want to integrate WaterScore data into their own infrastructure — not query it per-address — we offer bulk data licensing. You get the complete graded dataset for 48,000+ US water systems, CCR contaminant extractions covering ~49.4% of the US population, and quarterly refresh delivery. Private well chemistry remains real-time via API (coordinate-dependent, can’t be pre-cached).

Pricing is based on coverage scope, refresh frequency, and distribution rights. Contact us to discuss.

Water quality intelligencefor every US address.