Rob Waghorn
Louise. If the are no signs of a blockage it could be a broken seal on a sanitary fitting. Is the bathroom on the ground floor? In cases where the bathroom is downstairs leaks can go undetected for periods of time because of location, (If a bathrooms upstairs and there's a leak it comes through the ceiling). It would need to be investigated by a trained drainage engineer/plumber There are lots of good drainage engineers on rated people and none should charge just to look and give advice. Hope this helps. Robert.
