Toilet bowl loses water after flush

[berniesmith]

Our newer toilet was installed professionally a few years ago, and now the bowl gradually drains water from it. If I flush normally, water spurts up. We found a way to flush it (not an excellent clean flush) by pressing the handle slowly until the bowl fills, then flushing. It works that way, but still loses water from the bowl after about half an hour (ends up with about 1 inch of water in the bowl). The tank seems to fill fine, and there are no leaks. Can you help me solve the problem? Thanks!

 

[jimbox]

sounds like you have two seperate problems here.

r.e. the post title sounds like you have a crack in the bowl somewhere, take a really close look, and have a peer under the flooring to see if you can see any dampness down there

 

[JohnD]

A UK trap would only lose water if there was a leak, or in weather conditions when strong gusts of wind led to fast-changing air pressures

We generally use a different design of WC trap over here, is yours like the American design? Which is a bit like a syphonic trap, but not the same as ours.