The original post said his bill went up $86. At $2 per 1000, that means your water consumption went up 43,000 gallons? For math sake a waste/good water from your RO unit of 4.3:1, that is 1,000 gallons of RO water in your tank or approx 330 gal per month you are replacing and your signature says you have a 70g tank. That is one heck of a evaporation rate, even if you did a 100 percent water change per month.
Check that toilet.