Southern Water has responded to claims regarding Weir Wood reservoir during the Sussex drought

With Ardingly Reservoir falling to just 17 per cent capacity, South East Water is reducing daily river releases under extended Environment Agency drought powers.

Operating as a standalone cornerstone of Mid Sussex’s supply infrastructure, the ‘critically low’ reservoir cannot rely on support from other regional sites.

As a result, questions and speculations have circulated online surrounding why nearby Weir Wood reservoir cannot be used to restore Ardingly’s capacity.

As of October 2026, the reservoir has fallen below 20% capacity (standing at approximately 19.4%) following hot summer conditions and the granting of an Environment Agency drought permit. (Image: EDDIE MITCHELL)

placeholder image — As of October 2026, the reservoir has fallen below 20% capacity (standing at approximately 19.4%) following hot summer conditions and the granting of an Environment Agency drought permit. (Image: EDDIE MITCHELL)

Southern Water were approached for a comment surrounding Weir Wood reservoir’s use.

A spokesperson at Southern Water said: “Weir Wood reservoir is being rebuilt to ensure long-term water resilience for the North Sussex region, in the face of climate change and population growth. 

"The existing treatment works date from the 1950s and reached the end of its operational life, with significant reliability and water-quality challenges. The site was therefore taken out of supply in 2018.

"While a number of options were considered, a complete rebuild was identified as the best long-term solution to provide a reliable and resilient water supply for customers in the area.

Ardingly Reservoir stores roughly 4.77 to 8.3 billion litres of water (part of South East Water's primary supply network. (Image: EDDIE MITCHELL)

"While we already supply water to South East Water through an existing interconnected network, Ardingly's current situation would not be resolved if Weir Wood treatment works were operational."

Although Weir Wood Treatment Works is currently out of service, Southern Water are rebuilding treatment works by 2030 to secure long-term water supplies.