I live in an apartment where we are experiencing noise from the above apartment that I can best describe as a toilet refilling. It occurs approximately every 2 to 2.5 hours everyday starting at around 6am and running through the day and evening and is coming from a room that has a toilet, shower and water tank. The duration of the noise is around 45 seconds to 1min 30secs. The problem is that a plumber has investigated and can't replicate the noise by flushing the toilet. I describe the noise as like a toilet refilling but it could be something else. Less regularly we also get a loud water squirting / hissing through the pipes noise as well. There are only two apartments per floor and its definitely coming from above, not next door.
So I'm keen for any ideas ... could it be that the toilet has a delayed refill and it happens some time after the actual flush? Could it be a leak, although if thats possible why would a refill from a leak make a noise but not a normal flush? Could it be something else like a hot water system? Do hot water systems refill that regularly but for short periods of time? Could it be from a higher apartment (we are on level 12 of 15 floors) and just happens to be causing an issue out our level, although strange that those above us wouldn't hear that?
Getting pretty desperate for an answer as the owners above don't really care so I need to come up with potential solutions to keep testing.
Appreciate any help.