Toilet Mystery

I'd guess the water pump was left on and the toilet fill valve was leaking by.

rdhetrick wrote:
I'd guess the water pump was left on and the toilet fill valve was leaking by.

Water to toilet comes from 2 places
Water Pump or City Water via hose

Toilet valve leaking thru

rdhetrick wrote:
I'd guess the water pump was left on and the toilet fill valve was leaking by.

That would only be true if he left the fresh water tank full while the TT was in storage, and there was more fresh water than the black tank could hold.

You might be missing one or both caps on the roof vents. If you look on the roof there are two 1-1/2" PVC pipes that come up thru the roof and have vent caps on them. One is black tank, one is gray tank. If the cap was missing, rainwater and/or melting snow will run down the vent and fill up the tank. Once the black tank is full it will overflow from the toilet. The gray tank usually backs up into the tub/shower since that's the lowest drain.

The water pump was not on and there is no water in the fresh tank.
The sensors on black tank show empty, and looking into toilet with flashlight shows very little water in tank. I know it sounds crazy, but these are the facts.
That's why I am stumped........ I will check roof vent caps though although my tank isn't full.
Thank you so far for the responses.

Perhaps you didn't relieve the pressure in the lines after shutting the pump off and water found an Avenue of least resistance, toilet valve.
But your right, not heard this one before.

Water intrusion through the roof vent would have to meet black tank capacity before threatening the toilet.

Was the toilet lid open? Check the plastic crank open vent right above the toilet for cracks. They dry rot over the years. If no water hooked to lines I'm guessing rain water from above.

Do you have the built in black tank rinser? Maybe you left the hose connected too long and the tank backed up into the toilet, then when you drained the tank the toilet didn't run back?

BurbMan wrote:
Do you have the built in black tank rinser? Maybe you left the hose connected too long and the tank backed up into the toilet, then when you drained the tank the toilet didn't run back?

If the seals pushed out enough to let water into the toilet, it surely it would have slowly leaked back down into the black tank. And the water would not have been clean if coming up from the black tank.

If he rinsed enough the water would be clear, but agree this is an unlikely scenario.

Most likely cause is that the OP filled the toilet with water meaning to put into a clean tank with a deodorizer, went outside to dump the tank, then forgot to come back and flush the toilet and deodorizer into the tank.

I vote 100% user error :)

Fossil Hunter wrote:
The water pump was not on and there is no water in the fresh tank.

Believe it or not, this is the second time in 5-6 years that I've read of this kind of toilet mystery. The first one was never solved either!

Is there any chance the fresh water tank isn't empty? A common occurrence is for city water to backflow through the water pump and fill the freshwater tank unbeknownst to the owner.

Though, with the pump off... I'm still not sure how it would make it into the toilet.