Why is hot waste water (shower, sink…) not reused for heating?

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Why is it not used again and wouldn’t it be very efficient to combine with a heat pump for reuse?
Especially since water from shower or sink isn’t usually very dirty, couldn’t it be stored for a while in an isolated tank so that e.g. a heat pump can run more efficient on it than on usually colder air or colder ground water?

In: Engineering

27 Answers

Anonymous 0 Comments

I want to say it can be reused. I think I recall a product in a solar home catalog back in the early aughts that acted as a heat exchanger between grey water and the clean water entering your hot water heater. It would preheat the water entering the tank, saving you a couple bucks a month or year, depending on how much hot water you use in a day.

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