Antifreeze is added to water and other liquids to lower their freezing point. Ethylene glycol is the most common automotive cooling-system antifreeze, although methanol, ethanol, isopropyl alcohol, and propylene glycol are also used. All can be toxic if ingested by animals or humans. Used antifreeze, through contact with an engine’s cooling system, may contain traces of fuel, oil, and metals (including lead, chromium and cadmium) which make it a potential hazardous waste. Depending on how antifreeze is managed and disposed, solid and hazardous waste management regulations as well as local municipal wastewater regulations will apply. Antifreeze should not be disposed of on the ground or down a storm sewer.
The Wisconsin Department of Natural Resources considers used antifreeze a Wisconsin-specific universal waste if it’s recycled. Universal wastes include commonly generated wastes that can be recycled, such as fluorescent lamps, batteries, thermostats and other mercury containing devices. If you choose not to recycle used antifreeze, you are subject to all applicable solid and hazardous waste regulations found in chs. NR 500 to 538 and 660 to 670, Wis. Adm. Code.
Do not mix used antifreeze with other solid or hazardous waste. Mixing used antifreeze with other substances such as oil or solvent may prevent its ability to be recycled and may cause it to be necessary to manage it as a hazardous waste
May used antifreeze be put down sanitary sewer drains?
Due to the levels of lead and other metals antifreeze commonly contains, discharging down sanitary drains is NOT recommended as a best management practice. It has been determined that approximately 40% of used antifreeze would be characterized as hazardous waste due to elevated levels of lead.
DNR’s publication “Managing Used Antifreeze” (PUB WA-356) summarizes the regulations and requirements that apply to used antifreeze.
This publication was prepared for environmental, health and safety staff at University of Wisconsin System campuses, to assist in finding resources and information for regulatory compliance. It is not intended to render legal advice.