wc pan running dry over long period All aspects of plumbing questions and answers, help, tips and information

[Tigger123]

returned from holiday to find the first floor ensuite wc pan empty. thought that it may have dried out due to the warm weather and the lid being left up. now noticing that this wc has reduced water in the pan come the end of the day. the system is 20 years old. the ensuite shower and wash hand basin doesn't have a problem, nor does the wc, etc in the bathroom which is next door. the house does not have a outside vented soil pipe and there is no sign of an air admittence valve in the loft area. as i said, the house is 20 years old and upto now has had no problem. any ideas please ?

[htg engineer]

If you have no air admittance valves then the water can be sucked from the pan when other appliances connected to the saem waste pipe ar used.

But I would check for damp around the base of the toilet, could be a brack in the toilet pan and water could be leaking under the pan and under the floor.

htg