CONSIDER THIS would you brush your teeth knowing your fresh water supply was contaminated? Would you take a shower knowing your fresh water was contaminated? Would you do your dishes knowing your fresh water is contaminated? If you answered NO to any of the questions THEN you need the RV INLINE SANITIZER. What are the perfect breeding grounds for bacteria? DARK, SHADED NONVENTILATED HEATED areas, YES, your water lines and holding tank ARE the perfect location for bacteria to grow, that’s why the RV Association suggests you sanitize your fresh water tank and water lines twice a season. Our RV INLINE SANITIZER is the only patented system available for this purpose, it is a brand new, much easier way to finish your sanitizing job. Our device has no moving parts, use a 13/16 open-end wrench to remove the fill plug, add your bleach, use the same 13/16 open-end wrench to tighten the plug securely, so that the little blue O ring can hardly be seen, remember, there must be a hose washer inserted below the fill cap and is tight against the canister fill opening plug. This easy to use canister should last a life time. Simply connect your water hoses to the canister add required amount of bleach and turn on your water supply. Remember, filters do not remove all contaminants from water; only bleach is the proven method. The canister uses two (2) regular hose washers, one is used on the top fill plug area and the other is used on the female intake area. THE BLUE WASHER IS SIMPLY TO USE AS A GUIDE FOR DEPTH. IF YOUR SYSTEM LEAKS ITS BECAUSE THE HOSES ARE NOT TIGHT AND THE TWO HOSE WASHERS ARE NOT IN PLACE. EACH UNIT IS TESTED WITH 65 LBS OF AIR. confirm that both hose washers are inserted into your canister.