This sink and shower additive eliminates and prevents offensive grey water odors in drains and vents. It prevents grease build-up in holding tanks. Grey Water Odor Control has a pleasant floral scent and is non-staining. It has no chlorine or solvents to damage valve seals and is environmentally safe. A 1/4 bottle effectively controls odors in a 40-gallon grey water holding tank. 24-oz. bottle.