Falling water levels in toilet pan

[sannesley]

We recently just installed a close coupled toilet with internal overflow. Over the last week we've noticed something a bit weird.

When we flush the toilet the water will settle at the level it's meant to be at in the pan. If we come back about an hour later the water level in the pan has dropped by about 2 inches to the point were sometimes its lower than the outlet on the pan where the waste dissapears when it's flushed.

On one occassion when I was on my knees inspecting this I could feel a breeze blowing up from inside the toilet but no smell associated with the sewer.

When this fall in water level happens there are no leaks in the area of the pan visible so I'm at a loss to understand where the water is going and what's causing it to drop in the first place

Any ideas on what could be happening or should I be worried about it turning into something bigger??

 

[Bahco]

Could be a blockage at the top of your soil pipe or AAV not working and the water is being siphoned out when other wastes are emptying.

See if the level drops when bath or sink is being emptied.

 

[Nige F]

Could be a strong wind comin`over the mountains and blowin across the top of the soil/vent pipe

 

[sannesley]

Could be a blockage at the top of your soil pipe or AAV not working

The set up we have doesn't use an AAV. We just have pipe venting. The new toilet is a close coupled cistern and pan and the location of the soil pipe was for an older toilet.

This means that the waste pipe from the old pan would have been farther out from the wall. This means that for the new close coupled set up the pipe leaving the new toilet has to go through a pretty steep bend using a flexible to get from the back of the toilet to the soil pipe in the floor.

This could be resulting in a blockage in our soil pipe where some of the absorbent material trapped is absorbing some of the pan water between flushes. I suppose we'll have to wait and see if nature takes it's course and breaks down the suspected blockage over time and flushing