The best ways to avoid generating unknown wastes include: 

• Label all secondary containers when adding material from stock containers.
• Inspect all chemical containers on a regular basis and address labels which are fading, peeling, or are otherwise becoming illegible - this includes stock containers, secondary containers and waste containers.
• Label all containers used to collect waste before adding the waste to the container.
• Use funnels or other means to pour chemicals from one container to another to avoid chemical contamination of the outer label which can make the labels illegible.
• Ensure all laboratory personnel label their secondary containers, intermediary or transfer containers, and product containers during all experiments, as well as all waste containers generated.
• Coordinate with EH&S to conduct proper laboratory cleanouts/closeouts when there is a change of personnel, location, or funded research within any given space.
• Avoid the collection of legacy materials which have not been used in five or more years.
• Routinely inspect for excessive storage that can accumulate over time - this includes ensuring spaces are secure to prevent others from using them as dumping areas for unwanted materials and equipment.