[Karsten]

BTW, I am collecting kitchen sink water as well. The drains are not connected yet, so the water just runs into a bucket that I have to empty outside. This water turns DISGUSTING fast.  [] . I would not recommend storing this type of water in a tank for much time. It will also cover the inside of the tank with a nasty slime.

[litespeed]

Waste water recovery is not very usefull if it is going to be reused as water.  However, warm shower and bath water can be heat exchanged back into the system easily enough. A fail safe system is needed of course to ensure water separation.

I actually designed one for my house just for the heck of it, but never got round to construction. I doubt the amount of heat recovery achieved would be noticeable in my mild climate. But where winters are long and cold it might be a good thing.  Probably alread been done someplace....