The unknown pipes
NYC's lead service line inventory looks like a public health story. Scroll through the density maps and it starts to look like something else — a decade-long construction program, block by block across the five boroughs.
Between the water main and your tap there's a buried connector called the service line. It runs under the sidewalk, through the building foundation, and up to your meter. You never see it. The city may not know what it's made of. The EPA's 2024 Lead and Copper Rule Improvements changed both of those facts: every U.S. water utility now has to publish a parcel-level inventory of every service line and its material.
anatomy of a service line
NYC's Department of Environmental Protection published the inventory. Here's what it shows — and why the "Unknown" column is where the story actually lives.
Every building in New York City connects to the public water system through a buried service line. The DEP's inventory covers ~856,000 of them — one per tax lot, across all five boroughs.
The heat map shows the full network's density. Pre-war Brooklyn, the south Bronx, upper Manhattan — neighborhoods built before World War II run hot. That density is also where the risk concentrates.
Filter to confirmed 🔵 lead service lines. ~117,000 properties — roughly 1 in 7 service lines in the city — have a verified lead pipe from the main to the building.
The EPA's 2037 replacement mandate makes every one of them a work order. Trench the sidewalk, pull the old pipe, run new copper, restore the concrete. A few days per property. Multiplied by 117,000.
Now look at the 🟡 Unknown lines — properties where the DEP has no record of the service line material. ~114,000 of them. Nearly identical in count to the confirmed lead.
The density pattern almost perfectly mirrors the lead map. The data void clusters in the same neighborhoods as the known risk — because the same factors that made record-keeping worse historically also made lead pipe more common: older housing stock, pre-war construction, neighborhoods with less political leverage to get infrastructure documented.
For every confirmed lead pipe, there's another that's a question mark. This is the public health crisis the "Find Lead Pipes Faster Act" was written to address.
Combine them. Confirmed lead + galvanized requiring replacement + unknown = 🔴 ~231,000 properties where the service line is either definitely bad or probably bad. That's ~27% of every service line in the city.
This map is the 2037 construction program. Every hot spot is a block where contractors will spend the next decade trenching sidewalks. At realistic crew rates — 2–4 replacements per crew per day — this is roughly 60,000–120,000 crew-days of work spread across 13 years. The largest coordinated residential pipe-replacement campaign in city history.
👷 The borough breakdown below shows where that work will land.
Where the work lands 🏗️
The replacement burden (lead + galvanized + unknown) by borough. Brooklyn and the Bronx carry the heaviest load — unsurprisingly, the boroughs with the oldest residential housing stock and the highest share of pre-war apartment buildings.
Down to the community district
Five borough bars flatten 59 community districts into a blunt average. Shade each district by its replacement burden — confirmed lead plus unknown lines — and the load resolves into a handful of hotspots: south and east Brooklyn and Staten Island's North Shore run darkest, the same pre-war, low-density-housing geography the heat map lit up.
Burden = confirmed lead + unknown per community district. Each line is placed at its tax-lot centroid (PLUTO), joined by BBL — 99.96% of the inventory matched a lot. Pre-computed at build time.
The full inventory
All service lines, by material classification. The "Non-Applicable" category covers properties where a service line relationship doesn't apply — commercial-only lots, city infrastructure, etc.
The math of the mandate ⏱️
The EPA's deadline is December 2037. That's roughly 13 years from the inventory publication. If the city replaces lines at a perfectly even pace:
⚠️ Assumes linear pace and ~250 working days/year. Real-world rates depend on inspections, property access, street restoration permits, and winter closures.
View underlying data
NYC service line inventory · by material
| Material | Count | Share |
|---|
Replacement burden · by borough
| Borough | Lines to replace |
|---|
Data sources & methodology
Primary dataset: NYC Open Data, dataset jqfp-uff7 — "Lead Service Line Location Coordinates."
Published by the NYC Department of Environmental Protection per the EPA's Lead and Copper Rule Improvements (2024). Material and borough totals are fetched at runtime via the Cloudflare Worker proxy; the
maps are pre-aggregated at build time (see methodology).
Total inventory: ~856,000 service lines.
Methodology: Borough is derived from the first character of the tbbl (tax block + lot) field: 1=Manhattan, 2=Bronx, 3=Brooklyn, 4=Queens,
5=Staten Island. "Replacement burden" counts Lead + Galvanized Service Lines Requiring
Replacement + Unknown. The inventory carries no coordinates, so each line's tax lot
(tbbl/BBL) is joined to NYC PLUTO (64uk-42ks) for a lot centroid and
community district — 99.96% of lines matched a lot. The heat
map bins those centroids to a 0.01° grid (≈1 km cell); the community-district map sums lead +
unknown per district. Both are pre-computed at build time (no runtime map traffic), so the lot
centroid stands in for the actual buried service-line location.
Caveats: The construction timeline math assumes a linear replacement pace and 250 working days/year — a simplification. Real sequencing depends on DEP inspection priority, property-owner cooperation, street-opening permits, and budget cycles. The "Unknown" share is a conservative lower bound on the actual lead pipe count; EPA LCRI guidance assumes a significant fraction will prove to be lead upon inspection. Statewide, New York has ~934,000 Unknown-classified lines.
Policy context: The Find Lead Pipes Faster Act and Lead Pipe Replacement Act (NY State) were both introduced because the LCRI-mandated open data made the Unknown blind spot quantifiable. The political response required the data to exist first.