Something I do that I haven't seen mentioned is that I keep a gallon-sized toy bucket in the kitchen sink. When I wash my hands or scrub potatoes or rinse off dishes for the dishwasher or whatever I do that would have sent almost-clean water down the drain, I do over the bucket. When the bucket is full (like 10 times a day) I throw the water out the front door into the flower garden. You'd be surprised how much usable water goes down the drain.