If you're cleaning paint thinner off your brushes after a DIY project and a bunch of it accidentally goes down the drain, you may be wondering how much harm you've done. How damaging can the paint thinner actually be to your pipes? Could you be fined? Could it start a fire? What should you do now to fix the issue, and how should you dispose of paint thinner in the future? We answer some of your most common questions on paint thinner.