Get a good toilet brush and simple brush around the opening in the bottom of the toilet (valve) and flush with water. More than likely something is caught in the rubber preventing a good seal. A microscopic bit of "you know" can cause a gap in the seal. A simple brush down the hole does wonders. Then a little lubricant (even a couple drops of vegetable oil) will help soften and seal the rubber and not damage anything. I'd avoid any lubricant with petroleum as petroleum can deteriorate the rubber seal.
If that does not help, then repeat a couple times. I bet you'll be fine. But if not, then you'll want to take stronger action, like replacing the seal, or even the toilet.
2005 Chevy Silverado 3500 Dually Duramax 6.6L V8 Turbo
Century Truck Cap Commercial /Toolboxes
Northeast Outfitters Canoe
It might be some toilet paper stuck in the seal, and letting water out, air up into the bathroom.
WHen my RV was 6 years old, just before the extended warranty expired, I had to have the seal replaced, and that fixed mine for several years. Now I have to pull up on the handle to keep the valve shut all the way, so it will hold water. I guess there is something causing it to stick a little open, or might be a worn gasket that is getting in the way from it closing all the way.
If pulling up the handle works, then this can work for a few years, but ultimately you will need to replace the valve.
I have used vinegar for several years to clean the mineral's from the Arizona water that builds up on the rubber seal. pour alittle in the bowel and let it sit.
2001 35 ft avalon alpenlite RK
2005 3500 2wd duramax CC dually
trailair center point suspension
JT Strong Arm Stabilizers
KSH 55 inbed fuel tank
Induction Overhaul Kit
TST tire monitors