Note the following from the article….
The company is investing £200m over the next five years on improving its pipe network and industry regulator OFWAT said UU did beat its leakage target by 5m litres a day and was ranked as one of the best performing companies in the UK.
UU has the largest area to serve in the UK of all the water companies. They have a lot more pipework to maintain and don't forget, it's a very rare thing for us to need a hosepipe ban, we're usually very lucky in the North West in that we have so much water we can usually sell some to the southerners. Leaks aren't a problem when your reservoirs are brimming over.