Each year the water and sewerage companies in England and Wales provide Ofwat with information on their performance against various aspects of service. Ofwat publishes a levels of service report which reviews the companies' performance in delivering customer service and in providing water supplies and sewerage services. The report compares companies' performance against industry averages. At reviews of price limits companies are rewarded for good performance and penalised for poor performance in delivering services to customers.
Companies take seriously how they compare against the industry average and to one another.
There are eight levels of service indicators covered in the report. These are known as DG2-DG9. The reference level is defined as 10 metres head of pressure at the boundary stop tap with a flow of nine litres per minute. There are exceptions to this to allow for circumstances beyond a company's control. For example, pressure problems can be caused by a customer's own plumbing.