Developers + AI agents

Every contaminant in every city's tap water. As JSON. No key.

1,633 U.S. public water systems, 180 contaminants, 46 states. Every value transcribed from the utility's own annual report and compared to the federal limit. Free, no key, no rate limit, CC BY 4.0.

Live

Try it in your terminal

curl https://www.thewatermap.com/api/water/ma/53-communities-in-the-mwra-service-area/2024

Returns the full structured contaminant facts for 53 Communities in the MWRA Service Area, MA — every measured value, the units, the statistic type (RAA / p90 / single), the sampling context, the federal limit.

Show response shape

{
  "dataset": {
    "name": "U.S. Drinking Water Quality",
    "license": "https://creativecommons.org/licenses/by/4.0/"
  },
  "system": {
    "name": "53 Communities in the MWRA Service Area",
    "state": "ma",
    "year": 2024,
    "contaminantsMeasured": 29,
    "contaminantsOverLimit": 2,
    "page": "https://www.thewatermap.com/water/ma/53-communities-in-the-mwra-service-area/2024"
  },
  "contaminants": [
    {
      "id": "pfhxs",
      "label": "Perfluorohexanesulfonic acid",
      "family": "pfas",
      "status": "over",
      "ratio": 4.0,
      "facts": [{
        "value": 0.012,
        "units": "ug/L",
        "statisticType": "raa",
        "standardValue": 0.003,
        "standardType": "mcl"
      }]
    }
    // …
  ]
}

1,633

Water systems

180

Contaminants

States

Endpoints

GET/api/water

Index of every verified system. Rolled-up status, lat/lng, links to the HTML and Markdown twins.

GET/api/water/{state}/{city}/{year}

One system's full structured contaminant facts. Same data the HTML page renders.

Full spec: /openapi.json · LLM Markdown index: /llms.txt

Wire it into Claude or Cursor (MCP)

Drop the MCP server into your agent and your assistant answers tap-water questions from the live, source-linked dataset:

You

Is the tap water in Pomona, CA safe to drink?

Claude (with MCP)

Pomona, CA's 2024 Consumer Confidence Report lists 3 contaminants at or above the federal limit, including TTHM at 1.4× the MCL. Full report → /water/ca/pomona/2024

You

Which California cities have lead over the federal action level?

Claude (with MCP)

In the 2024 reports indexed, 14 California water systems report lead at or above the EPA action level. Top three by ratio: …

Request access below — early MCP integrations get a direct line to the team.

Already using it for

Real-estate overlays

Show water quality on a property listing. Match address → city → /api/water lookup.

Filter recommendation

Pull the city's CCR contaminants. Recommend a filter that targets exactly what's there.

Research notebooks

Join the contaminant table to demographic, geographic, or health data. CSV-ready via JSON.

Higher volume? Building something cool?

The public API is rate-limited at the CDN edge — fine for most use cases. If you need a higher ceiling, the MCP server, or a webhook when new reports are approved, drop a line.

Public JSON above is live and free. CC BY 4.0 — attribution required for redistribution.