[mbarrett]

There are a few more parts you can buy for the home install to make it more efficient. I can see the manufacturers leaving it out due to install space and cost.

My system is relatively new, but this thread has my thinking of ways I can better use that 4 gallons of waste.

[SixSigma]

That's handy to know. I was investigating whether I could make my hydroponics system recycle the water but the waste ratio made it unattractive - it was only for science.