Have noticed that the stop valve is leaking in my parents four year old home. The valve is an Apex Limiting Stop Valve (this one http://apexvalves.co.nz/pressure/pressure-limiting-stop-valve-20mm/)
The leak is coming out very very slowly through the blue cap - where you would adjust the pressure. I might have expected a leak from one of the seals (where the pressure/filter body fits in) or at the input/output. But it seems like water should never come out of the blue cap. There's a bit of build up of rusty water on the blue cap and drops on the dwang below.
I cleaned the filter (for the first time) and there was only a few tiny grains or sand in it.
Is the filter unit buggered?
Is it unreasonable to expect it to be replaced by the original plumber?