Data Sources & Methodology
Where this data comes from
Every result on this site comes from a government source, published because federal or local law requires it — never from a prediction or estimate. Each state's sources have real differences worth stating plainly rather than folding into one generic description, so they're listed separately below, one state at a time.
New York
- New York State Department of Health — the statewide lead service line inventory, required under the EPA's Lead and Copper Rule Revisions. Reproduced with attribution per NY DOH's data use policy.
- NYC Department of Environmental Protection — New York City's own, separate inventory, required under NYC Local Law 65 (2019). We use this one specifically because it's typically more current for NYC addresses than the statewide dataset alone, and because roughly 43% of New York's population lives in the five boroughs — improving coverage here has an outsized effect on how many people this tool can actually help.
When both New York sources cover the same address, we show the more current NYC-specific record rather than the statewide one.
California
- California State Water Resources Control Board (Division of Drinking Water) — the statewide service line inventory, required under the EPA's Lead and Copper Rule Revisions.
California reports very few confirmed lead lines statewide, but real, substantial galvanized-pipe risk — which this site treats as seriously as lead, since galvanized lines downstream of a lead connector can leach lead particles even after the original lead pipe is gone. If you're checking a California address, the galvanized-risk ranking is often more informative than the lead ranking.
Utah
- Utah Division of Drinking Water — the statewide inventory, required under the EPA's Lead and Copper Rule Improvements. Utah's own statewide dashboard explicitly excludes every water system serving 50,000 or more people, so this alone leaves out most of the state's largest cities.
- Salt Lake City Public Utilities, Granger-Hunter Improvement District (West Valley City / Taylorsville area), Provo Power & Water, City of West Jordan Utilities, City of Orem, South Jordan City, and Logan City Water Division — each of these excluded from the statewide dashboard publishes its own separate inventory, which we've incorporated individually.
A handful of other Utah cities over the 50,000-population cutoff (Sandy, St. George, Layton, and Lehi, among others) don't currently publish a bulk-accessible inventory we could incorporate — these are real gaps, not addresses we've checked and found safe.
What this doesn't cover yet
This tool currently covers New York, California, and Utah, and even within those states, coverage isn't complete — some water utilities and buildings haven't published inventory data yet, or publish it somewhere we haven't incorporated. A missing result means we don't have data for that address yet, not that the address has been checked and found safe. If your address doesn't appear here, your water utility is required by federal law to have its own inventory available — these are real places to go directly:
- New York: find and contact your local water utility directly via NY DOH's own public water system contact finder.
- California: the State Water Resources Control Board runs its own official interactive lead service line map, which may have address-level detail we haven't incorporated yet.
- Utah: the Division of Drinking Water runs its own official statewide lead water line dashboard, and larger cities not listed above may publish their own address-lookup tool worth checking directly with your water utility.
How we're expanding coverage
We're working on this in a few concrete ways:
- Adding city- and utility-specific datasets where they exist and are more complete or more current than the statewide feed — NYC DEP's dataset above is the first of these.
- Finding individual water utilities' own published data. A number of utilities maintain their own public inventories beyond what gets aggregated into the state dataset. We're identifying these one at a time and adding the ones with real, meaningful coverage.
- Using federal data to find the real gaps. The EPA maintains its own utility-level summary of every water system nationally. We compare that against what we've actually loaded to see precisely which utilities are under-represented here, so effort goes toward closing real, known gaps rather than guessing.
- Requesting records directly from utilities that haven't published complete public data, where the gap is significant enough to justify it.
What we won't do
We don't predict or estimate a service line's material for addresses marked Unknown. Some other tools use statistical models to guess at unreported lines — we think a factual public record and a modeled guess are different things, and we only show the former. If we don't have a real record for your address, we'll tell you that plainly rather than offer a prediction dressed up as an answer.