The waste water systems in your RV (Motorhomes, Fifth wheels or trailers) are very similar to your home systems. They have p-traps, roof vents and fixtures (toilet, drains, etc). The main difference is that you have HOLDING TANKS for your Gray water and Black water (sewage waste). You need a way to periodically dump these holding tanks to a safe and approved waste removal system.  Failure to do this properly can cause disease or death for you, your family and possibly a lot of other people.

RV Waste Holding Tanks

Waste water consists of both Black water and gray water. The term black water refers to the waste flushed down the toilet and stored in a separate tank, referred to as the black tank. Gray water is the wastewater from sinks and shower drains and is stored in the gray tank(s). Waste tanks most often empty through a single external outlet, but a single valve controls each tank so you can decide which one to dump.
The black water dump valve should remain closed even if connected to an exterior sewer hook up. For proper dumping, empty the black water tank only when it is nearly full. Some people close both valves and empty them both at the same time, dumping the black water first. The idea is to send a large volume of water through the tanks and hose at the same time to assist the solid waste in flushing from the system.  However, since many people today have washing machines, dishwashers and take long showers, leaving  the gray water tank closed could be an inconvenience.

RV Waste Holding Tank Dumping Instructions

1. Put on a pair of rubber gloves that come up high over your wrists and are folded back to avoid water entering your shirt sleeve.
2. Place the end of the sewer hose into an approved dump station inlet using the proper adapter to avoid spillage, if necessary.
3. Twist off the termination outlet cap on your RV. (Make sure the valves are shut first.)
4. Connect the sewer hose by turning counterclockwise, locking the end levers over the termination end.
5. Open the black tank termination valve and drain. (If you have a manual valve, hold the valve housing as you pull the handle out to avoid possibly pulling pipes apart.)
6. If you have an external water flush connector, connect a (non-potable) hose to rinse the black water tank. If not, flush your toilet a few times to empty it better. Ever so often, fill the tank a couple times and empty it to flush out all the residual “stuff”.
7. Close the black tank termination valve.
8. Open the gray tank termination valve and drain. (If RV has 2 gray tanks, drain one at a time.)
9. Close the gray tank termination valve(s).
10. Disconnect sewer hose and store.  Use the non-potable hose available at the dump station to rinse your sewer hose before you disconnect it from the dump station inlet. Avoid touching the water hose to the sewer hose. If you had a full tank of gray water you might avoid this flushing.
11. Replace termination cap on the outlet.  Double check that both valves and any master valve are completely shut closed.
12. Add chemical deodorant / breakdown agent approved for RV use through your toilet.

After the sewage tank has been emptied, close the gate valves and put approximately five gallons of water in the sewage holding tanks. This will help prevent solids from building up

RV Toilet

The toilet operates from water supplied either by the fresh water tank or from an exterior water supply connected to a campground water hook-up. (The water pump must be turned on when utilizing the water from the fresh water tank.)

The toilet flushes directly into the black water tank. You should find complete instructions and care for the model installed in your RV at the manufactures web site or by calling the company.

Solids Build-Up

The most common problem associated with the waste system is solids build up. Using plenty of water when flushing the toilet, and keeping the black water holding tank valve closed until ready to flush the system can reduce the risk of build up.

Should you ever have a build up of solids, close the valves, fill the tanks at least 3/4 full with fresh water, drive a drive a few miles to agitate the solids then drain the tanks. Some people add ice cubes prior to driving to provide some “scrubbing” of the tank.

Do not EVER put these things into the RV toilet:

1. Facial tissues, paper towels, sanitary products (including those labeled flushable).
2. Detergents or bleach. Use a sewage tank deodorizer.
3. Automotive antifreeze, ammonia, alcohols, or acetones.
4. Grease from cooking, table scraps or other solids that may cause clogging.
5. Toys.

Keep the lid closed on the toilet, especially if you have small children to avoid health problems with pets and children.