We moved into a new build, double storey townhouse about 6 months ago. The gravity fed water tank was overfilling out the roof due to a faulty ball valve.
The building plumber repaired this fault, but since then the cold water to the basin, bath and power shower has been about 10 % what it was. I checked all the taps and valves were reopened in the loft. I assume it is not a blockage at the taps, as all the outlets have poor pressure
Any ideas please as to what the problem is and how I rectify it?