Emergent Metering
Book a Demo

Apartment water submetering

Multifamily Water Submetering

Meter each apartment's water so every resident pays for what they use, leaks show up unit by unit, and the building's water bill stops being a fixed overhead.

In most multi-unit residential buildings, one utility meter serves every apartment and the owner pays the bill. Water and sewer are then either absorbed into rent or recovered with an estimate. Multifamily water submetering replaces the estimate with a measurement: a meter on each unit's supply, read remotely, with each resident billed for their own use. This page is part of our submetering guide.

Why owners submeter apartment water

  • Cost recovery. Water and sewer are among the largest controllable operating costs in multifamily property, and they rise every year.
  • Behaviour. Residents who see their own consumption on a bill have a reason to report a running toilet or a dripping tap.
  • Leak detection. A unit with continuous flow at 3 a.m. has a leak. A building meter cannot tell you which unit; apartment meters can.
  • Fairness. A single occupant in a one-bedroom stops subsidising a family of five next door.

RUBS vs true submetering

A ratio utility billing system (RUBS) divides the building's water bill using a formula — floor area, number of occupants, number of bedrooms, or a combination. It needs no hardware and can start immediately. Its weakness is that a resident's bill barely changes whatever they do, so it recovers cost without changing consumption, and it gives no information about where water is going.

True submetering measures each unit. It costs hardware and installation up front, but it links bills to use, gives residents a reason to conserve, and turns every apartment into a leak detector. Many owners use RUBS for common-area water such as irrigation and laundry and submeters for the units themselves. Either way, local rules on how utility charges may be calculated and disclosed apply — check them before choosing.

What the install involves on existing plumbing

The deciding factor is plumbing layout, not the meter. Walk the building before pricing.

  • One supply per unit. Newer buildings, and many garden-style buildings, feed each apartment from a single line with a shutoff. One meter per unit goes at that point.
  • Multiple risers per unit. Older mid-rise buildings often run several vertical risers, each serving the kitchen or bathroom of a stack of units. Each unit then needs a meter on every riser branch that feeds it, which multiplies hardware.
  • Hot and cold. Where hot water comes from a central plant, meter cold and hot separately, or meter cold only and allocate hot water — hot water meters need a temperature rating to match.
  • Access. Meters must be reachable for service; behind a finished wall needs an access panel.
  • Cut-in or clamp-on. Mechanical meters are cut into the line by a licensed plumber with a short shutdown per unit. Clamp-on ultrasonic meters avoid cutting the pipe and suit larger lines and common-area branches.

Which meters fit multifamily water submetering

Apartment supply lines are typically 5/8" to 1". Small-bore positive displacement and multi-jet meters with pulse output are the usual choice; ultrasonic meters suit larger lines and retrofits where cutting the pipe is a problem.

See every option in water meters and ultrasonic flow meters.

Reading the meters and billing

Manual reading of dozens of meters every month does not last. Pulse outputs from each meter are counted by a data collector — a high-density pulse module wired to a group of meters, or a wireless transceiver such as the ModHopper where running cable to every unit is impractical. Readings are uploaded on a schedule and used to produce each unit's charge.

  • Bill on a fixed read date and keep raw interval data so disputes can be checked.
  • Reconcile the sum of unit meters against the building meter; the gap is common-area use and leaks.
  • Set a continuous-flow alert per unit so leaks are caught before the bill.
  • Follow local rules on disclosure, fees and how charges are calculated.

The full chain from meter to bill is described on utility submetering systems.

Scope apartment water submetering

Send the unit count, pipe sizes and riser layout, and we will specify meters and data collection for the building.

Request a scope & quoteTalk to an engineer215-645-7141

Multifamily water submetering FAQ

What is multifamily water submetering?
Multifamily water submetering puts a meter on the water supply to each apartment so each unit's consumption is measured, instead of the building's single utility meter being split among residents.
What is the difference between RUBS and water submetering?
RUBS (ratio utility billing system) estimates each unit's share of the building bill from factors such as floor area or occupants. Submetering measures each unit's actual use. RUBS needs no hardware; submetering ties the bill to behaviour and exposes leaks unit by unit.
Can apartment water submetering be added to an existing building?
Usually, if each unit is fed from an identifiable supply line. Buildings with one riser per unit are straightforward; buildings where several risers feed each unit need a meter per riser or a different approach.
How are apartment water meters read?
Meters with pulse output are counted by a data logger or wireless transceiver and read remotely; network-connected meters report directly. Manual reading is possible but rarely practical at scale.
Is it legal to bill apartment residents for water?
Rules differ by state and sometimes by city, covering disclosure, fees, meter accuracy and how charges are calculated. Confirm local requirements and lease terms before billing.