There is a structural oddity in how New York City buildings relate to their own water data, and it is written into the rules rather than being an accident of practice.
The ownership rule
Under 15 RCNY §20-05(b)(3), once meter work is accepted, the New York City Department of Environmental Protection owns, maintains, repairs and reads the service meter. The meter on the service entrance is municipal equipment sitting inside a private building.
The consequence is easy to miss because the bill arrives on time every quarter. What the owner has is a charge. What the owner does not have is a flow record they control — no interval history, no ability to add a channel, no way to see which riser or which tenant or which cooling tower the consumption came from, and no access to the instrument itself.
Electricity does not work this way in practice. Owners routinely install their own current transformers behind the utility meter and build whatever measurement topology they want. Water in New York City has no equivalent default, and most buildings never close the gap.
Owner-side submetering is the only route to a flow record the owner controls. That is not a sales line; it follows directly from who owns the service meter.
What the water actually costs
New York City bills water and sewer per hundred cubic feet (ccf). One ccf is 748.05 gallons. Sewer is charged as a percentage of water — currently 159%.
| FY2026 | FY2027 | |
|---|---|---|
| Water | ~$5.05 (derived) | $5.35 |
| Sewer | ~$8.02 (derived) | $8.51 |
| Combined per ccf | $13.07 | $13.86 |
| Year-on-year | +3.7% | +6.0% |
Rates adopted by the New York City Water Board: FY2026 on 6 June 2025, FY2027 on 10 June 2026. Only the FY2027 schedule publishes water and sewer as separate line items; the FY2026 split above is derived from the combined rate and the 159% sewer ratio, and is labelled accordingly.
The arithmetic on a leak
This is where the case for owner-side measurement is made — not with a percentage, but with multiplication anyone can check.
A continuous flow of 1 gallon per minute runs 525,600 gallons in a year. That is 702.6 ccf. At the FY2027 combined rate:
> 1 gpm continuous = $9,738 per year
A flow small enough that nobody notices it — 0.1 gpm, about six gallons an hour, a weeping valve or a running fill — costs:
> 0.1 gpm continuous = $974 per year
Neither of those shows up as an alarm. Both show up as a baseline that never returns to zero overnight, which is exactly the shape a flow record makes obvious and a quarterly bill hides.
There is a second line worth knowing about. Because sewer is charged as a proportion of metered water, water that demonstrably evaporates rather than entering the sewer can be the basis of an evaporation credit where substantiated — cooling towers being the common case. At the FY2027 sewer rate:
> $8,510 per year in sewer charges per 1,000 ccf of substantiated evaporative loss
Substantiating it requires a measurement record. The service meter will not produce one.
Why we will not quote you a savings percentage
Most vendor pages on this subject carry a number like "buildings typically save 15% on water with continuous monitoring." We are not going to, because on 10 October 2026 we went looking for a credible non-vendor source for that class of claim and there isn't one:
- EPA WaterSense at Work, section 2.1 on metering (November 2023) — contains no savings figures at all.
- FEMP Best Management Practice #1 and FEMP's water metering resources — none.
- Alliance for Water Efficiency, 2023 evaluation of AMI leak notification across four utilities and roughly 190,000 meters — explicitly excludes commercial and institutional accounts. It covers single-family, multi-family and dedicated irrigation, and its own authors caution that it is a difference of means with no control group.
- LBNL report 1005988 (August 2016) — reports 5–50%, but for residential customers and utility-side non-revenue water. Nothing commercial.
So the honest position is: the evidence base for commercial continuous water monitoring is empty, and any percentage you see quoted is marketing. The arithmetic above, by contrast, is just rate times volume and you can verify every term of it.
One thing water monitoring does not do
Water savings do not improve a building's Local Law 97 position by a single tonne.
The emissions associated with treating and conveying municipal water sit with the water utility — upstream of the building, in Scope 3 terms. They are real: roughly 2,700 kWh per million gallons on a lifecycle basis for New York City water, which works out to approximately 1.06 tonnes CO₂e per million gallons. That figure comes from Congressional Research Service report R43200 citing Twomey and Webber (2011), so it is a secondary source and the tonnage conversion is ours.
But none of it lands in a building's LL97 calculation. Anyone presenting water conservation as LL97 relief has made an error, and a consultant reviewing the filing will find it. Water savings are worth money on the water and sewer bill. That is the case, and it is a good enough case on its own.
Separately, Local Law 84 benchmarking requires water reporting only for flagged buildings, not universally — worth confirming your own status rather than assuming either way.
What a measurement topology looks like
For a building wanting a flow record it controls:
- An owner-side meter downstream of the DEP service meter, sized to the service, giving a total the owner can read
- Riser or zone meters where tenant allocation or leak localisation matters
- Dedicated metering on cooling tower make-up and blowdown where an evaporation credit is in scope — the credit needs make-up and discharge, not just make-up
- Pulse or Modbus output into a data concentrator. Note that two pulse inputs on a typical gateway will not carry gas plus water; if both are in scope, the concentrator is not optional
- An interval record, because the diagnostic signal is overnight baseline flow, which a daily or monthly total erases
Emergent Metering supplies this hardware — mechanical and ultrasonic water meters, pulse and encoded registers, Modbus and pulse concentrators, gateways and enclosures.
Frequently asked questions
Who owns the water meter in a New York City building? The Department of Environmental Protection. Under 15 RCNY §20-05(b)(3), once the meter work is accepted, DEP owns, maintains, repairs and reads the service meter.
Can a building owner install their own water meter? Yes — downstream of the DEP service meter, as owner-side equipment. That is the normal route to a flow record the owner controls, and it does not disturb the municipal meter.
What does a small continuous leak cost in New York City? At the FY2027 combined water and sewer rate of $13.86 per ccf, a continuous 1 gpm flow costs about $9,738 a year and a continuous 0.1 gpm flow about $974 a year.
How much water will monitoring save my building? We don't know, and neither does anyone quoting you a percentage. There is no credible non-vendor study of continuous water monitoring savings in commercial buildings. The defensible case is the cost of a leak you cannot currently see, which is arithmetic rather than an estimate.
Does water submetering help with Local Law 97? No. Water-related emissions belong to the water utility, upstream of the building. Water submetering pays back on the water and sewer bill, not on the LL97 calculation.