Paint thinner can be brought to the Clermont County Fleet Management Garage at 4000 Filager Rd. M-F, 8-2:30. (513) 732-7775. Limit 5 gallons per day. The thinner can only have small amounts of paint in it. If the thinner has been sitting for a few days, then suspended paint should have settled to the bottom and you can decant off the thinner and then dry and dispose of the paint residue in the same way you would paint.