Dear Dave,
Every time my friend goes camping with us, his trailer has plumbing issues. He seems to believe that when his galley gray tank becomes full it then begins to empty into his black tank (two days of camping). Every time we camp, he needs to empty his black tank into a tote to take for disposal and then his galley works well.
My question is this: Does this sound normal that his gray tank would begin to drain into his black tank? —Robert, A friend’s 2022 Springdale
Dear Robert,
You did not provide the floorplan model so we can’t get the specifications of holding tank sizes and the quantity. However, you did state the “galley gray tank,” so does he have a separate holding tank for the kitchen?
As I have stated many times, I have learned to never say never when it comes to how RV manufacturers design, or, sometimes more accurately, throw together RV systems.
Black and gray tanks are usually completely separate
Typically the black and gray water tanks are completely separate even if there is more than one gray holding tank due to floorplan configurations. The gray holds the cleaner water from the shower and some sinks, again, depending on the floorplan and location of the sink. The black water tank is predominately toilet water.
There should be no “overflow,” as the tanks are separate. However, if you leave the dump valves open in both and have either a cover on the main dump bayonet or separate dump valve, the water level will backflow from underneath due to gravity to the lowest point or holding tank.
It could also be just a valve or valves that look closed, but are not seating properly and allowing a slight escape of fluid.
If the vent pipes of each tank are connected going up to the roof and have just one vent at the top, when the black tank gets full, it could be rising up the vent and causing a vacuum.
These would be the only two points that I could see any type of connection or similarity.
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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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