Agreed. RO filters and membranes aren't super cheap either. Just toss the old water and spray with the new RO water. I don't have an RO system just because it would not be practical for me. i only have 2 tanks to mist every day or so. my local grocery store sells RO water for 49cents a gallon. i can fill up my 2 gallon jug for under a dollar and it usually lasts me about a month or two.you will also be replacing filters and ro membranes at an alarming rate if your trying yo "recycle" it. your better off disposing of the excess water (preferably with some sort of passive draining system such as drilled holes w/ bulkheads at the desired water level) and using the ro water (from processed tap) to supply the mister.