A £10m treated-water reservoir at Chaul End, near Caddington in Bedfordshire, has almost doubled storage capacity at the site, according to Affinity Water.
The new facility provides around 20 million litres of additional storage, taking the total capacity from just over 21 million litres to approximately 42 million litres. The extra capacity is intended to give the utility more flexibility to move water around its network during periods of high demand or disruption.
Storage within the drinking-water network
Unlike reservoirs that collect water before treatment, Chaul End stores treated water ready for distribution to customers. Affinity Water said the investment will strengthen supplies serving Luton, Hemel Hempstead and St Albans.
Ben Hayward, Affinity Water’s head of capital delivery, said: “Chaul End is a major investment in the resilience of the areas water supply.
“By almost doubling the amount of treated water we can store at the site, we have created a much stronger buffer to help us manage periods of high demand and disruption, particularly when pressure on water resources and the wider network is at its greatest.”
The project forms part of the utility’s Connect 2050 programme, which aims to secure supplies as the population grows and climate change increases pressure on water resources.
Hayward said the reservoir’s value had been demonstrated during the hot and dry summer of 2026, when water resources were under significant pressure. He added that lessons from Chaul End were being applied to the delivery of the Hadham Hill and Hill reservoirs.
Precast construction and environmental measures
The reservoir was delivered in partnership with OCU Group using a standardised system of precast concrete components manufactured away from the site. Affinity Water said this reduced the amount of construction activity required on site.
The scheme was built on Green Belt land with measures intended to protect and improve the surrounding environment. These include new grassland and wildflower areas, native hedgerow and scrub, and replacement and additional planting to increase the biodiversity value of land previously used for agriculture.
Additional storage at Chaul End is also expected to help Affinity Water use water transferred from Grafham Reservoir in Cambridgeshire more effectively, reducing the amount taken from local groundwater sources and leaving more water in the environment for the region’s chalk streams, the utility said.
OCU operations director Denis Leahy said: “Chaul End shows what can be achieved through close collaboration and a repeatable approach to delivering strategic water infrastructure.
“By using a standardised precast concrete system, with key components manufactured off site, we reduced on-site activity while supporting safe, efficient and high-quality delivery. The experience gained at Chaul End will help inform future strategic storage projects, and we are proud to have worked with Affinity Water to strengthen water-supply resilience for customers and the environment.”
Link to future water supplies
Chaul End is also intended to support Affinity Water’s longer-term plans to bring new sources into the region. The proposed Grand Union Canal transfer is planned to bring water from the Midlands into the company’s supply area by 2033, with the reservoir providing additional storage to help move water to areas where it is needed.