How have we got to "change the ball valve,end of" from a water leak on the ground floor in a 2 storey house with tanks in the roof space? What sort of advice is that
It happened at my brothers house. Leaky ball valve allowed the tank to overflow, overflow pipework was damaged so water leaked from the loft, through the middle of a stud wall (so no water to see on first floor), and then through the ceiling into the lounge.
It's worth a look. Using the water during the day would mean the level in the tank is constantly dropping. Go to bed at night and a leak from the ball valve could top the tank up to the overflow height. I'd get up in the loft in the morning and go & see where the water level is in the tank. It's a 5 minute check to definately rule it in or out.