New York City water tank inspection results 2015-2017

Map by Ben Jay and Frank G. Runyeon

This interactive map is part of a City & State investigation that reported widespread neglect in the thousands of weathered wooden tanks that supply drinking water to millions of New York City residents. A review of city records indicates that most building owners still do not inspect and clean their tanks as the law has required for years, even after revisions to the health and administrative codes that now mandate annual filings.

The New York City Department of Health and Mental Hygiene, which is responsible for overseeing the water tanks, said the wood tanks are not a cause for concern. But scientists at the federal Environmental Protection Agency and public health experts consulted by City & State warned that animals can easily get into New York City’s water tanks, that mucky sediments inside the tanks may contain pathogens and that poorly maintained water tanks could be the source of disease outbreaks.

There are still many thousands of water tanks across the city for which there is no information at all. The city can’t even say with certainty how many there are or where they are located, much less their condition – even well-maintained water tanks accumulate layers of muck and bacterial slime.

Read the full investigation here.

About this map

As far as we know, this is the first-ever map of water tanks in New York City. We mapped over 13,000 water tank inspection reports that the city Department of Health and Mental Hygiene (DOHMH) provided to City & State in March 2018 via a Freedom of Information Law request. The inspection data mapped above covers reporting years 2015, 2016 and 2017. Every year, building owners and water tank cleaning companies are required to submit this information to the city as proof that they inspect their tanks annually and test them for bacteria – rules designed to keep water tanks safe for New Yorkers to drink from. Owners must submit a report as proof before Jan. 15 of the following year. If no report is filed, the city considers that evidence that the tank was not checked for sanitary or structural defects.

Disclaimer: This map is based on government data current as of March 27, 2018. City & State cannot guarantee the accuracy of the information presented here beyond the data we used to create it. The map should be used for informational purposes only and you should request the inspection records from buildings you are interested in. The latest data is available through this city portal: Rooftop Drinking Water Tank Inspection Results.


Where Are The Tanks?

Blue: all the buildings that reported to DOHMH that they definitely have a drinking water tank. Since the 19th century, the vast majority of these tanks have been made of wood – mostly yellow cedar, some redwood – the rest are metal.

Yellow: buildings that the city estimates likely have a drinking water tank, though they don’t know for sure. This highlights every New York City building seven stories and taller without a tank inspection report.

Uninspected tank likely

These buildings have not reported a water tank inspection to the city, so we do not know for certain that they have a tank. That said, the city assumes that every building taller than six stories requires a tank to provide adequate water pressure. This is how DOHMH has estimated the total number of buildings with water tanks in the city. These buildings are marked in yellow to give a fuller picture of the city’s estimated universe of water tanks. Using the satellite view, perhaps you can visually confirm whether the building has a water tank on the roof. Remember, many buildings choose to hide their tanks behind tall walls or inside decorative enclosures.

Water Tanks Inspected

You have four options to view which tanks filed inspection reports: 2015, 2016, 2017, or All. Selecting an individual year will display all buildings who filed an inspection that year in green; and all buildings who did not file an inspection that year in red. Selecting “All” will display buildings who filed every year in green; and buildings who failed to file in at least one year in red.

Sanitary Conditions: Sediment? / Biological Growth? / Insects or Debris? / Bird or Rodent Activity?

It’s normal for tanks to accumulate sediment and biofilm between annual cleanings, but most water tank inspections describe suspiciously spotless water tanks. This is likely because many inspectors record tank conditions after they clean and disinfect the tank. We mapped the few results that show sanitary defects in city records. Even elite addresses find issues in their tanks, including evidence of insects, birds or rodents. These reports likely tell us more about the inspector’s honesty and interpretation of the city rules than the tanks’ condition relative to reportedly pristine tanks.

Bacteria: Coliform / E. coli

This shows the results of bacteriological testing of the building’s water. Many buildings don’t test their water tanks for bacteria until after they clean and disinfect them. Because of this, few reports find the two types of bacteria that the city requires building owners to test for: coliform and E. coli. Positive results display red, meaning they found bacteria, and negative results display white, meaning they did not find bacteria. Finding either of these bacteria in your water is bad news. They are indicators that there may be dangerous microbes in the water supply. E. coli is of particular concern because it is a sure sign that fecal matter is present.

Satellite View / Roadmap View & Clear Overlays:

You have two options for viewing the map by clicking the “Roadmap View” / “Satellite View” button. When you zoom all the way in on Satellite View, you see an aerial photograph of buildings. You’ll notice that the color overlays continue to show the building “footprint.” If this is distracting, you can remove the overlays by selecting the “Clear Overlays” button. Remember to click it again so you can view the overlays as you move around the map.

Government Links and Resources:

Here’s the city information page about water tank inspection reporting.

You can check a building’s most recent inspection filings through the Health Department’s portal.

For a primer on how NYC laws governing water tanks have evolved, see here.

If you want to complain to the city about your water quality or a water tank, you can call 311 or file a complaint online.

Your Right to Know

You have a right to request drinking water tank records from any building owner in New York City. Within 5 business days, the building owner must provide copies of records for the last five years of water tank inspections and water quality tests. (§141.07 Building Drinking Water Storage Tanks)

Find something important? Have a tip? See a problem?

Let us know if you find a water tank that’s a concern. Contact us at

Data sources:

This data was provided to City & State on March 27, 2018 by the NYC Department of Health and Mental Hygiene in response to a FOIL request. Other city data was used to create this map including data from the Department of Buildings, Department of Information Technology & Telecommunications and Department of City Planning.

Reports for the following addresses could not be mapped:





To view the details of these inspections, visit the city’s portal: Rooftop Drinking Water Tank Inspection Results