Drain Disposal
General Rules for Drain Disposal

The following general rules apply to drain disposal of chemicals from laboratories at UC Berkeley*. Laboratory disposal of chemicals is limited to occasional disposal of small amounts of chemicals, as detailed in the guidelines below. Large scale or continuous disposal of any chemical is permitted only with the written approval of the Hazardous Waste Management Committee. (The Office of Environment, Health and Safety should be contacted to obtain this approval.)

• Only water-soluble substances shall be disposed of in the laboratory sink. Solutions of flammable solvents must be sufficiently dilute that they do not pose a fire hazard. Solutions should be flushed down the drain with an appropriate amount of water.
  
  (NOTE: A compound is considered water soluble if it dissolves to the extent of at least 3%. In general, a soluble substance that contains a substance that is not soluble should not be poured down the drain. However, if the water-insoluble material com prises less than about 2% of the mixture, drain disposal is usually acceptable because the small quantity of water-insoluble material will be well dispersed in the aqueous effluent.)
• Strong acids and bases should be neutralized or diluted to the pH 5-10 range before they are poured in the sewer system.
• Highly toxic, malodorous, or lachrymatory chemicals should not be disposed of down the drain.