Plumbing

Finding a leak - cold water pressure test conflicting results

Anonymous user 16/03/2024 - 2.36 PM

Hi, appreciate any help or ideas on the below. I suspect there's a underfloor leak as I have a damp patch on the wall, rotten floorboards and skirting boards between the bathroom and the living room. Leak tracing (gas, thermo, acoustic) concluded there is no leak despite the pressure tests indicating a drop in pressure. The pressure test is done by connecting the gauge instead of the washing machine and normally on shutting the stopcck the pressure drops from 2-2.5 bars (while no taps or toilet are leaking) to 0 in around 1 min. However lately I realised that when doing the pressure test first thing in the morning (before using any water) the pressure does not drop. After the use of taps or flushing the toiler the pressure again starts dropping rapidly. It is a one bedroom ground floor flat with a combi boiler. Could these changes in pressure be caused by a water leak or should I look elsewhere? Many thanks