What does it mean when one fllushes the toilet, the tank empties, the
water level comes back up to its normal level and seems stable, but when
one looks at it an hour later, almost all the water is gone from the
bowl? The water level is just where the porcelain ends on the far side
of the bowl. In other words, the opening is full of water, but the
water goes no higher. .

FWIW, this is not a low-volume toilet. It's happened three times in a
row.

I do have the water supply turned almost off so it normally takes a half
hour for the toilet tank and bowl to fill, but it's been working like
that for years.


Another interesting thing about this toilet is that just after it
finishes flushing, I hear thunder from somewhere. Well it sounds like
thunder or like the way the special effects man would imitate thunder
during radio dramas by taking a piece of sheet meal and shaking it.

But what's strange about this is that there's another toilet in the
next bathroom, back to back with this one, with only a stud and
sheetrock wall in between, using most of the same pipes, and it doesn't
make this noise.


*I had the same occurrence many years ago and asked a plumber about this. His response was "Capillary action" If I remember correctly. He said sometimes toilet tissue gets hung up in the drain tube and water will drip down that paper and siphon the water out of the bowl. His advice was to pull the toilet and clean it out from underneath. I never did and I think it eventually stopped.