Breaks down waste and tissue. Stops odors up to 7 days. No harmful formaldehyde. Septic tank safe. Camco's TST Blue Enzyme RV Toilet Drop-ins contain a bacterial/enzyme complex that will digest waste, tissue, fats and proteins and only activates in the presence of material requiring digestion. Unlike normal enzymes, TST Blue chemistry provides a stable product with a long shelf-life that is not temperature sensitive. Each drop-in treats 40 gallons. It contains a buffer system to prevent acid formation as well as septic odors and has a Pure Rain fragrance. All components are biodegradable.