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Environment, Health and Safety

Drain Disposal Guidelines

Even if a chemical is not a “hazardous waste” by the USEPA definition or listing, the town and city wastewater discharge permits for the North and South Campuses, respectively, do not allow hazardous chemicals down the sink or other drains.

The ONLY aqueous solutions in normal laboratory volumes (<1 gallon) that may be drain disposed must have a pH between 5 and 9 and DO NOT CONTAIN:

  • Carcinogens
  • Toxic chemicals
  • Heavy metals (e.g., arsenic, barium, cadmium, chromium, lead, mercury, selenium, silver, etc.)
  • Cyanides or sulfides
  • Organic solvents (whether miscible or not)
  • Viable infectious agents
  • Radioactive substances

Examples of Solutions Acceptable for Drain Disposal:

  • Physiological saline, inorganic buffers (phosphate or bicarbonate based), TRIS, or other such organic buffers at use concentrations, sugar solutions, and non-toxic salts in dilute form
  • Liquid blood, serum, or plasma from animals or humans not known to contain pathogenic organisms or liquid blood, serum or plasma known or suspected of containing pathogenic organisms may be drain disposed after disinfection using a 1:10 dilution of bleach for at least 30 minutes or as described in each labs SOP's and protocols.
  • Liquid tissue culture media, fresh or spent supernatant, which has been rendered non-infectious, including culture media containing serum additives such as fetal calf serum
  • Solutions containing disinfectants at used concentrations, such as 0.5 % bleach, may also be drained disposed
  • Ethanol concentration of 24% or less



Do Not Drain Dispose, But Containerize as Hazardous Waste:

  • Aqueous phases of organic solvent separations
  • Miscible water solvent mixtures, e.g., acetone/water
  • Aqueous mixtures with alcohols (methanol, ethanol greater than 24%, etc.)
  • Histological preparation materials (Formalin, staining solutions, Xylene containing clearing agents)
  • Ethidium bromide solutions

Note: Gels (agar, electrophoresis plates, gelatin) that contain hazardous substances of biological, chemical or radiological nature must be containerized and disposed of as hazardous waste. If they do not contain hazardous substances, they do not need to be containerized, but they should not be disposed of through the drain system. They could clog and stop the drain. In addition they can provide a coating on the pipes that will allow bacterial growth and subsequent colonization of “drain flies” that are very difficult to eradicate.

If you have further questions or are requesting special approval for drain disposal, please contact EH&S at 829-3301.