Grey Water Odor Control Is Formulated To Eliminate And Prevent Offensive Odors In The Drains, Vents And Traps Of Your Sinks, Showers And Grey Water Holding Tanks. Designed Specifically For RV Holding Tanks, These Strong Formulas Ensure Powerful Year-Round Odor Control. Available In Convenient Easy-To-Use Forms, These Products Give You Maximum Performance With Minimum Effort.