We are soon to put in rainwater tanks, but an interesting point I have heard is about airconditioners. We have a raised house and are about to install three airconditioners. We were going to place the condenser units on the ground, but we have decided to wall mount them outside. That way, the water that the airconditioner collects and pumps out can drip straight into our rainwater tanks.

Apparently, you can even drink the stuff as it is essentially distilled water. I don't know how much water we will get out of them, but every drop counts hey?