Mystery leak.

[RevKev5064]

This is my very first post to the forum and I have appreciated reading all of the helpful comments. Thank you for letting me join.

I have a 2000 National RV Sea Breeze. I have just begun using it and working out all of the kinks, replacing washers and fixing leaks. However, I have a very strange one that I cannot seem to figure out. When I connect the city water, one of my gray water tanks fills up to overflowing in about 24 hours. All of the faucets are off and sealed. I found out because when I went out to the RV today, the bathtub was running over... I have no idea what could be leaking into that tank. It does not seem to do it when the pump is on, only when the city water is connected. (I have a pressure regulator installed.)

I have looked at the plumbing diagram and I cannot see anything that could suggest a leak into the holding tank from the city water connecter. My RV has an elaborate valving system for filling the fresh water tank or city water, water heater bypass, and that sort of stuff but I cannot see anything that would lead to my situation.

Any thoughts on where I should begin looking?

Thank you,
Kevin

[dougrainer]

You have a 20 year old Motorhome that who knows what has been modified in that 20 years.
1. The Plumbing on a National is simple like most RV's.
2. Since your problem is NOT when on Water Pump, That means you probably connected to a Tank Flush Inlet that was added to the Gray tank. Nationals back in 2000 did not have a Gray Flush and a Black Flush. usually just a Black flush.
3. In 20 years it is possible that someone added a extra valve system to connect to the tank flushes by just switching a valve and not having to unhook the City Water fill hose and then connect to the Flush connection. Doug

[Matt_Colie]

Does the gray tank have a rinser that could be leaking?

I've seen that one.

Matt

[time2roll]

Do you have a reverse osmosis water filter?
I believe RO will put water down the waste pipe. Seems like a lot but maybe it is leaking or uses a lot to fill the reservoir tank.

[prichardson]

Two possibilities. If you have a single connection for both the city water and filling the fresh water tank; a valve in in that system may not be seating. It is also possible that the check valve in the water pump is not seating and allowing back flow thru the pump.

[Bobbo]

Since the fresh water line doesn't connect directly to any waste tanks, you need to look to all of the drains for the water source into the gray tank. Shower. Kitchen sink. Bathroom sink. One of them MUST be leaking.

[RevKev5064]

No, I do not have a washing machine. I just went back and checked the plumbing diagram and it does not have provision for a washer either.

Thank you.

[wa8yxm]

Do you have a washing machine? a properly installed washer will "overflow" into one of the gray (Wash most likely) tanks. if the solenoid valve fails.