Recycling heated waste water
Don’t let your energy dollars go down the drain.
A drain water heat recovery (DWHR) pipe is a simple technology to save on energy used to heat water. This pipe takes advantage of the warm water flowing down the drains to preheat the water going into the hot water tank. Preheating the water reduces the amount of energy needed to heat the water to the set temperature.
The technology is simple. Cold water coming into your house runs through a series of coils that are tightly wrapped around your drain stack. The heat from the drain water is transferred through the copper walls of the heat recover unit to warm the cold water before it goes into the water heater.
The heat is transferred but the drain water never mixes with the fresh water.
This simple technology has no moving parts and is long-lasting.
A study by the Canadian Centre of Housing Technology stipulates that DWHR pipes are most effective when you have large “drain water events,” where a lot of warm water is being drained, mostly from the shower, sink, clothes washer and dishwasher.
For a practical overview of water heaters, read our Water Heater Guide [PDF - 2.8 MB].