Purchase powdered water softener mix, powdered laundry soap and household chlorine bleach at your grocery store. These homemade RV holding tank chemical ingredients can be found in the laundry products aisle. Most RV systems will require about two boxes of softener. The water softener helps solid waste loosen up from the sides of the tanks.
Hook up your RV to water and sewer outlets, and have a hot water source available. With your RV tanks empty and the sewer valves closed, take 2 cups of water softener product and dissolve them into a 1-gallon bucket of steaming hot water.
Use your funnel to pour the water softener mixture down kitchen drains first, followed by your bathroom sinks, then into the toilet. Next, pour 1 cup of laundry detergent into the toilet tank. Adding laundry soap to the toilet tank will provide extra cleaning action. You do not need to add laundry soap to your gray water tanks, because these compartments regularly get enough detergents inside during normal use. You can leave this homemade holding tank chemical inside your tanks, until they are full again.
Proceed to use your RV waste water tanks normally. When they are about halfway full, add about 1 cup of bleach to your holding tanks. This final step will sanitize your tanks by killing off accumulated bacteria in your waste water. Adding bleach will also eliminate any odors resulting from normal use. Continue using your RV as usual, following normal waste water elimination procedures. Repeat the process as instructed above.
