Thank you for your purchase. The RV Inline Sanitizer is meant to be used between two hoses. Attach the fresh water hose to the front end of the canister by turning/spinning the canister onto the fresh water hose using FRONT end of canister.  Now attach the hose going to the RV water tank by turning the swivel head of the hose onto the REAR end of the canister.  Now your RV Inline Canister is attached to both the fresh water hose and the RV tank hose.  Now attach both hoses to their proper water fixtures. MAKE SURE YOUR HOSES ARE TIGHT ON TO THE CANISTER TO AVOID BLEACH SQUIRTING OUT.  Now open the fill plug using a 13/16 open end wrench, add the desired/required amount of bleach to the canister, the cavity will hold 7 ounces however you can add nearly as much as you wish as once the cavity if full, the position of the hose openings allow you to continue pouring as any access simply starts to run and fill the hoses and once the water is turned on, the bleach will flow into the RV holding tank.  Note return the fill plug and tighten with the same wrench, turn fill pug all the way in. Now that you have added the bleach, open the fixture going into your holding tank and then turn on the fresh water supply and in about 3 to 5 gallons of fresh water, your bleach is transmitted into your holding tank. Follow your  “HOW TO BLEACH YOUR FRESH WATER TANK” instruction or go to the internet for how to bleach your water lines using your on board water pump for instructions for your particular vehicle.  Once you have the desired amount of bleach and water needed, you can remove the canister from the hoses and restore into the original box until needed again. 

NOTE: Bleach kills Coronavirus, algae growth and bacteria.