The level of treatment our water undergoes before being pumped into supply depends on where it comes from.

Generally water from aquifers is already of high quality because it has been filtered through many layers of chalk or sand and needs only disinfection with chlorine.

Water from rivers and reservoirs contains a range of substances which need to be removed through several processes.

See below to find out how a typical water treatment plant works:

Screening 

Water drawn from rivers and reservoirs is passed through screens to remove any floating debris such as leaves, twigs or plants.

Auto-coagulation

The water is then pumped to contact tanks where a chemical coagulant is automatically added. This helps solid material in the water to settle.

Clarification

The water is then fed into clarifier tanks where the settled solid material in the water settles and is removed in the form of sludge.

Disinfection

Following coagulation and clarification the water is disinfected using carefully controlled amounts of chlorine.

Filtration

The water flows into rapid gravity filters where it passes through layers of anthracite, sand and gravel about 1.5 metres deep. Carbon filters can also be used to remove tiny traces of pesticide which occur in river water.

Chlorination

A final check is made on the chlorine levels and additional chlorine added before the water is pumped into supply.

Tap water

Exceptionally high quality water flows through water mains via covered storage reservoirs to your taps.