How Do You Dispose of Paint Thinner?

Reuse it first. The Missouri Department of Natural Resources says you can recycle used thinner by placing it in a jar until the paint particles settle, then using a coffee filter to strain out the particles, which will allow you to reuse the thinner.

The EPA says improper disposal of household hazardous waste can include pouring it down the drain, on the ground or into storm sewers, or in some cases putting it out with the regular trash. Montgomery County, Maryland, tells residents not to place flammable or combustible liquids or hazardous materials such as paint thinners in the trash, and says improperly disposed materials can cause fires in trash cans, on trash trucks and at its transfer station and recycling center.

Solvent rags can catch fire on their own. The Washington State Fire Marshal cites NFPA figures showing that on average 1,700 home fires a year are caused by spontaneous combustion from chemical reactions in flammable and combustible liquids, with rags responsible for at least 900. It advises keeping oil-based paints and flammable and combustible solvents in their original containers, tightly capped, and placing contaminated rags in a metal container once dried and storing it in a cool, dark place. The US Fire Administration advises keeping oily rags in airtight containers away from heat sources, and keeping anything that can burn at least 3 feet from furnaces, water heaters and other heat-generating equipment.