There can be lots of reasons behind leaking pipes: it might be that they are old or damaged; cold weather can freeze and crack them; and tree roots and even building work can cause damage.
If I had a leak or burst after the water has gone through the meter, do I have to pay for that water?
If you are unlucky enough to discover a leak on either your internal or external pipework that sends your meter into overdrive, you are entitled to claim for the cost of the water lost during the time you had the leak.