What Happens If You Accidentally Pour Paint Thinner Down the Drain?

brush getting cleaned in dish of clear liquid

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.

What is Paint Thinner Anyway?

Paint thinner is a compound that is most often made of mineral spirits, turpentine, and acetone. It's used to thin paint, and often to clean paint and stains off of brushes and other painting tools. A little bit of paint thinner can go a long way, and it can actually be reused, so don't buy more than you need for your latest DIY project.

Repeated Use

You can use paint thinner more than once. To do so, soak tools until they are clean and then let the paint thinner sit for a few hours or even overnight. Paint and other dirt will settle at the bottom of the paint container. The paint thinner on the top of the container will be clean and available to you to re-use.

You can pour it into a new container and seal it, marking it as safe to use again as paint thinner. You should also seal the dirty paint thinner in a separate jar or the original container to properly dispose of later.

two paintbrushes in a container of paint thinner

Will it Damage My Pipes?

If only a small amount of pipe thinner made it down the drain, chances are it won’t do too much harm to your pipes. Large amounts of paint thinner, however, can contaminate local groundwater, which is why some municipalities fine or punish people who dispose of paint thinner incorrectly.

Soapy Water

If you accidentally flush some paint thinner down your sink, try to flush it out by running hot, soapy water down the drain for 5-10 minutes, or longer if it was more than just a little bit. This should clear the paint thinner out of the system. If there's a stopper in the sink, make sure to remove it before running the hot, soapy water down the drain.

How to Properly Dispose of Paint Thinner

metal containers with yellow tops

When you feel you can't get any more reuse out of your thinner, there's a specific procedure for properly disposing of it—you should always do this rather than pouring it down the drain.

The paint thinner will need to be disposed of at a hazardous waste collection facility. These facilities usually accept sealed paint thinner containers. You may want to call ahead of time, though, to make sure that the facility closest to you will accept it.

You could also check automotive repair shops and gas stations. Some of them will have tanks for used oil and other fluids. These stores are sometimes paid when these materials are picked up by companies that convert them into usable oil. Your paint thinner could fill the tank, which would help the repair shop or gas station get paid faster. Call ahead of time, though, to make sure the store will accept your paint thinner.


Similarly, rags soaked in paint thinner must also be disposed of at a hazardous waste facility rather than simply thrown away. Put them in an airtight container along with water. The rags on their own are prone to combustion. Alternatively, you could store them in a fireproof container without water.

Warning: Tossing paint thinner in the trash is a fire hazard. An empty container can be thrown in the trash if it is dry and does not have much paint residue on the bottom but full containers need to be brought to a hazardous waste facility.