Water Meter Turning Constantly

[Old UKPF 127887]

Hi,
my sons water meter keeps turning whilst no water being used. Switching off internal stopcock stops the meter. But no sign of water internally.
useage bill has doubled for last 6 month’s so a sizeable amount of water disappearing.
Could this be a meter fault, bu5 why stop when stopcock off.
any ideas/suggestions welcomed.
thanks

 

[Ben-gee]

If you have any push button toilets you may find one is letting by and constantly running into the pan. Often can see a ripple in the water in the pan but not always.
Dry the back of the pan and then rest tissue paper there, you’ll soon see if the flush is letting by.