Drain Water Heat Recovery - a simple way to save money

Save up to 30 per cent on your water heating bill

Water heating is the second highest energy expense for most homes – and most of that heated water washes straight down the drain. A Drain Water Heat Recovery system recovers heat from warmed drain water. It pre-heats the cold, fresh water feeding into your water heater, from 8°C to about 23°C.


  • Reduce energy costs by up to 30 per cent as the clean water going into the water tank is pre-warmed and requires less energy to heat.
  • Maintenance-free, with no moving parts.
  • Easy to retrofit into existing homes.

How it works

A Drainwater Heat Recovery System pre-heats the cold water going into your water heater.

DWHR builder
  • Cold water comes into your water heater in copper pipes.
  • The cold-water pipe is coiled around the pipe that drains hot water from your showers and sinks.
  • Drainwater and fresh water never mix.
  • As hot drainwater flows down the drainpipe, 60 per cent of the heat is transferred to the cold fresh water pipes wrapped around the drainpipe.
  • This pre-heats the clean, cold water flowing into your water heater, from 8°C to about 23°C.

Selecting a drain water heat recovery system:

Speak to a TSSA-registered contractor to help you fully evaluate your hot water needs and water flow requirements.

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