- no more than a cup - down the drain with plenty of water.
Some hazardous household wastes can be flushed down the drain as long as they are followed by plenty of water. This recommendation applies if a hazardous household waste will be neutralized by water or if the municipal or sanitary sewage system is able to remove the toxins or render them harmless. This method is not recommended for people who have septic systems. Heavy concentrations of certain chemicals in a septic tank can destroy the microorganisms that make the system work properly.
Call your local waste-water treatment plant before you flush hazardous household waste down the drain to be sure that the water can be neutralized by their system. Follow their recommendations.