Do you dispose of different types of chemicals? If so, you run the risk of mixing incompatible chemicals together in your waste containers. Refer to this chart (EPAChemicalCompatibilityChart) to help determine what you can put in the same waste container. The chart is fairly complex, but the topic is also fairly complex. Always be sure to use secondary references such as Safety Data Sheets to verify that your chemicals are compatible–the EPA chart is general, not specific.