Hi , is it a new system and or has any work been done on the soil( waste water ) pipe?
No, property is 100's years old, rest of the toilets in the property are fine - we are connected to a septic tank which was emptied a few months back.
Its a strange one. Have you replaced them loo or any part of the cistern?
no, just flush the system, everything washes away, then the level of the water in the bowl continues to drop leaving a shallow amount of water at the bottom, repeat the flush, same thing ...
Some toilets are syphonic . they need a special valve in the cistern . if you had it replaced with a normal one this could be the problem
Hi ,if happy with your answer could please rate it , thanks