Tintin
Member
I have dual flush toilet that fills correctly to the right spot and then drains about an inch or so of water when the toilet is finished filling. I've replaced the fill valve and there no leaks in the toilet or or drain. One reason I've heard is that the vent pipe could be clogged, but from what I can tell it isn't. The one thing that is suspect though is down the line there's a small section where there's some reverse grade (which I eventually need to fix)...could that be acting the same as if the vent pipe were clogged...meaning if that section is half filled with water could that be the cause of the vent not completely venting and causing the toilet to lose a bit of water?