The Camco TST 12 oz. Orange Drop-ins are an effective and environmentally safe way to treat your RV's septic system. Simply drop one unit down the RV's toilet to stop odors and treat the water tank. No harmful formaldehyde, pesticides, or biocidesHighlightsDrop a packet into your RV toilet to break down waste and tissue, and treat both black and grey water tanks. Drop a packet in the black tank with every flush. You only need to fill the tank with a gallon of waterStops odors for up to 7 days The best chemical for treating your black tankFresh citrus scentEnvironmentally friendly - safe for septic tanksContains 12 packetsBuy it from Home Depot, Lowe's, Walmart, or order it from Amazon