We have a very small flat, where the living room, kitchen& a big cupboard with the boiler, washing machine&dryer are all in the same room.
Lately, there has been a noise coming from this cupboard every two or three hours.. it sounds like the "bloop" sound you get from a full sink when you pull out the stopper (hope it makes sense).
I have had men checking the kitchen sink (which is on the other side of the cupboard) and the walls around the appliances, but there's no leak and the walls are dry.
Is this noise normal & nothing to worry about?