Could the very water we drink today have quenched the thirst of Londoners over a century ago? Here at the Walton Advanced Water treatment Works, the answer is a resounding yes. The Walton Advanced Water treatment Works, initially commissioned in 1907, stands as a testament to London’s evolving relationship with its lifeblood: the River Thames. Originally built alongside the Knight and Bessborough Reservoirs, the works began its life using slow sand filtration, a tried and true method of the time. Imagine workers meticulously laying sand in those early filter beds, a scene captured in a 1909 photograph now preserved in the Thames Water Archives.
By 1925, London’s thirst had grown, and so did the Walton Advanced Water treatment Works. A new double filtration plant, designed by Henry E. Stilgoe, was erected. This innovative system used primary filters with coarse sand to remove larger particles, followed by secondary filters with fine sand for a more thorough cleanse. The process was ingenious, with compressed air and water used to clean the primary filters. The secondary filters required a more hands-on approach: draining the water and manually scraping off the sediment. This meticulous process ensured clean, safe drinking water for a rapidly growing city. Aerial photographs from 1926, part of the “Britain from Above” collection, offer a glimpse into the layout of this expanding waterworks.
The Walton Advanced Water treatment Works even had its own riverside wharf, complete with a two-tonne electric crane, used for unloading vital supplies like coal and sand from barges. As London continued to expand, so too did the works, with additional filter beds added in 1950 and a new water source, the Queen Elizabeth II Reservoir, incorporated in 1962. By the 1980s, the works could treat an impressive 135 Ml/day.
The Walton Advanced Water treatment Works has always adapted to challenges. Algal growth in the reservoirs proved problematic for the primary filters, so in 1992, Thames Water implemented a pilot plant using a cutting-edge system called Counter Current Dissolved Air Flotation and Filtration (CoCo-DAFF). This system, along with ozonation and granular activated carbon contactors, helped tackle taste and odor issues caused by algae. Today, the Walton Advanced Water treatment Works remains a vital part of London’s water infrastructure. It is one of five treatment works feeding the Thames Water Ring Main, the circulatory system that keeps London hydrated. The works continue to evolve, incorporating modern technologies like solar panels on the site of decommissioned filter beds, ensuring Londoners have clean, safe water for generations to come.