Every drop of the 535 million litres of water we supply each day is treated and safe to drink, even though just four per cent of it is used for drinking or cooking.
Generally, water from boreholes is already of high quality because it has been filtered through many layers of chalk or sand, so it only needs disinfection with chlorine.
View our film to discover the journey your drinking water takes before arriving freshly at your tap.
Water from rivers or reservoirs contains a range of substances which need to be removed through several processes at our water treatment works.
More than 600,000 tests are conducted on our water each year to ensure it remains among the best in Europe.
Once the water has been treated, it arrives at our customers' taps through 13,753 kilometres of water mains (that's almost 1,000 kilometres longer than the diameter of the Earth).