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

My instincts are that the amount of heat you could recover from the wastewater would never justify the amount of plumbing you’d have to do to set this up. Maybe if you have a tankless water heater you could preheat the city water a little with a heat exchanger… but drain lines have to be huge to avoid clogging so this thing is going to be large, expensive, and not all that efficient.

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