Solvents

Solvents are often liquids, though they may also be gases or solids, capable of dissolving other substances. Solvents are dangerous waste that commonly designate as toxic and ignitable. Learn how to properly handle, manage, and dispose of solvents safely and correctly.

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How to manage solvents

Designate solvents

Businesses need to designate solvents. Many solvents designate as dangerous waste.

These common solvents found in many businesses are either considered listed waste or characteristic waste or both:

Degreasing solvents (such as large scale 1,1,1-trichloroethane, methylene chloride, trichloroethylene) list as F001 due to toxicity.
Waste methylene chloride used as paint thinner or paint sludge stripped from parts equipment lists as F002 when it's been used or contaminated by a solvent. If unused and discarded, it's listed as U080.
Waste gun cleaning solvent or paint thinner (such as toluene or MEK) lists as F005. If the flash point is below 140° F, it's considered ignitable (characteristic D001).
Sludge or “bottoms” from solvent stills that recycle gun cleaner or thinner (such as toluene or MEK) also list as F005 and are considered ignitable (characteristic D001).
Waste or expired oil-based or solvent-based paint is considered ignitable (characteristic D001). It also designates as a Washington state-only waste due to metal content.

Use proper containment

Follow the guidance outlined for dangerous waste containers and ensure that you:

Use secondary containment for any container or still that holds liquid.
Electrically ground solvent containers.
Properly store solvent-contaminated wipes (also known as shop towels).

Regulatory considerations

It's important to be aware that other agencies besides Ecology regulate businesses that use solvents:

Local fire authorities regulate solvent storage since many solvents can explode and burn.
Washington State Department of Labor and Industries and Washington Clean Air Agencies monitor businesses that use either large amounts of solvents or small amounts of dangerous solvents since many solvents are toxic and release vapor quickly.

Choose safer, less-toxic solvents

Choosing safer, less-toxic solvents can benefit you and your staff by reducing potential health risks and keep harmful substances out of the environment. Water- or soy-based solvents are often good options.

Frequently asked questions

While businesses can use solvent stills to recycle spent solvent, we recommend reducing solvent use and finding safer alternatives first. By doing so, a still may not be necessary. However, if you find you must continue to use solvents that produce dangerous wastes, you may want to purchase a still to recycle your spent solvent on-site.

Distillation units may require a permit or authorization. Check with your local air authority, building permits with your city or county, and local fire authority for requirements. For a list air authorities, refer to Ecology’s Air Permit web page.

Use our Guide to On-site Distillation to help you learn if this process is right for you and how to choose a still.

Search through these databases to find more information on solvent substitutions:

CleanerSolutions is a general solvent substitution database.
CleanGredients is a database of commercial cleaning products and solvents chosen for superior environmental characteristics.
Safer Choice is an EPA industry program with an emphasis on safer cleaning and solvents.
Institute for Research and Technical Assistance is a California nonprofit that researches alternatives to toxic substances. Their reports page contains data about evaluations of newer solvent technologies.

Businesses that recycle solvents on-site must manage spent solvents as dangerous waste when it’s stored or accumulated before distillation. Because solvents are often reclaimed and reused multiple times, it is only necessary to count the largest amount of spent solvent accumulated at one time before recycling during that month.

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Contact information

Need help?
Contact a dangerous waste inspector in your region