The drain valve, or your RV’s dump valve, is the spot where all your plumbing pipes for the holding tanks come together in your RV. Sewage from the black and gray water tanks are plumbed to this valve to allow you to dump the waste at an approved dumping station. Ideally, the material from your holding tank moves through the pipes and into an external tank on site without any leaks or slowdowns. Any problems with the flow of the sewage materials can signal an internal problem with your RV’s dump valve.
The first place to check is the fittings themselves. You may have a cracked pipe or a loose connector that’s allowing material to leak out underneath the valve. If the fittings are tight and the pipes are undamaged, you’ll need to inspect your RV’s dump valve itself.
This plastic valve is designed to close off the individual tanks from emptying using a sliding spade valve. When you’re ready to empty your tanks, pulling the lever or handle of your RV’s dump valve slides the spade valve out, opening the pipe and allowing sewage to flow through. When it’s closed, it’s supposed to hold back everything in the tank as it seals to the oval rubber gasket inside the valve.
Any foreign objects such as pieces of plastic, garbage, or anything else that won’t dissolve (like the wrong type of toilet paper) can get wedged into a sewer valve, preventing it from closing completely and allowing liquid to leak out. Alternatively, storing your RV for long periods of time can cause the material in your RV’s dump valve to dry out and become stiff and difficult to open, or cracked and not able to seal properly. Always add drain valve conditioner to the system when storing your RV for any extended period of time. If you continue to have leaks in the sewer system, you may be able to check your valves if you have an external access port. Otherwise, taking the system apart to look for valves that are stuck or clogged may be the only answer.