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?

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Anonymous 0 Comments

This can be done. I don’t know too much about it, but I believe it is a relatively new idea and probably slow to take off, but wherever there is a source of heat, it’s probably being looked at as a heat pump source. I think the idea is to run the heat pump refrigerant line set through the sewage pipes, so it captures that heat before it goes off to the sewer. Probably best done in a large commercial project where there’s a reliable source of effluent.

Also there this low tech domestic solution someone else pointed out that seems pretty smart: [https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Water-Heat-Recovery-Unit-R3-48/203456041](https://www.homedepot.com/p/Power-Pipe-3-in-x-48-in-Drain-Water-Heat-Recovery-Unit-R3-48/203456041)

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