Submetering at the Water Heater
Last reviewed September 2026NES Editorial, checked by the Billing & Compliance team
Where a meter sits relative to the water heater decides how you bill each unit for hot water.
How do you submeter a water heater?
Submetering a water heater means installing a meter to measure the hot water a unit consumes. The placement matters. The ideal spot is the incoming cold water line just before the water heater, because every gallon entering the heater becomes a gallon of hot water, and a standard meter handles cold water well. When that line is not accessible, a special hot water meter, built to take the higher temperature, goes on the outgoing line after the heater. Both setups give an accurate per-unit reading to bill from. NES installs the meters, collects reads wirelessly each day, and bills residents monthly for exactly what they used. This is one of the better ways to keep rent flat instead of raising it to cover climbing water costs. Most owners see payback in 12 to 18 months, and total billing never exceeds your master-meter cost.
Before or after the heater
There are two valid meter positions. Before the heater, on the incoming cold line, is preferred because a standard meter reads cold water accurately and the volume in equals the hot volume out. After the heater, on the outgoing hot line, requires a meter rated for higher temperatures and is used when the cold line cannot be reached. We pick the placement during the site survey based on your plumbing.
What the meter buys you
- Per-unit hot water billing tied to actual use.
- Daily wireless reads that surface leaks early.
- A reason to hold rent steady instead of raising it for water costs.
- Payback that typically arrives in 12 to 18 months.
Related questions
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Thinking about submetering your property?
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