Three Valleys Water is the UK's largest water-only company in England / Wales. Operating for more than 130 years it supplies parts of Bedfordshire, Buckinghamshire, Essex, Hertfordshire and Surrey and the London Boroughs of Barnet, Brent, Earling, Harrow, Hillingdon and Enfield.

Three Valleys Water supplies 877 million litres per day to 3 Million customers.

In 1993, VWS provided an 80 MLD expansion of GAC filters at Iver WTW for a total treatment capacity of 240 MLD, including an ozonation plant house to replace traditional chlorine dosing.

The region around Iver WTW continues to grow and effluent regulations continue to tighten.

VWS provided an additional 87 MLD of treatment by providing two Actiflo® AC10 package units complete with associated chemical dosing facilities, in one-third the footprint required for a traditional GAC plant.

VWS also modified and upgraded the existing washwater and sludge handling system to incorporate the construction of a new sludge thickener tank.