Ministers have been warned that several reservoirs in England face the risk of running dry in the weeks leading up to Christmas, potentially affecting water supplies to homes and disrupting certain operations in the southwest and Sussex regions. The government’s emergency committee, Cobra, has been convening up to twice weekly to address the developing situation.
A confidential "reasonable worst-case scenario" assessment indicated that water levels in reservoirs such as Wimbleball in Somerset and Ardingly in West Sussex could fall to zero, a point referred to as "day zero." Wimbleball, which serves more than 400,000 people, currently holds approximately 13 percent of its capacity, while Ardingly, supporting around 280,000 customers, is at 17 percent capacity. Alongside household impacts, officials have raised concerns about potential operational disruptions at HMP Exeter and ongoing construction work at the Hinkley Point C nuclear power station in Somerset.
Water companies Southern Water, South East Water, and South West Water have requested government approval for non-essential water use restrictions, which could limit activities such as commercial car washes, watering sports fields, and refilling private pools. Environment Secretary Dame Angela Eagle is reviewing these applications as drought conditions persist.
The drought, exacerbated by summer heatwaves affecting roughly half of England, has been most severe in the southwest and Sussex. While recent rainfall from the early named storms Austen and Boelo has offered some relief, officials stress that regular monitoring and management efforts remain critical. Daily coordination meetings and ongoing Cobra sessions are focused on preventing any reservoir from reaching critical depletion.
Government sources have indicated that measures implemented by South West Water and South East Water have pushed back the anticipated "day zero" threshold for Wimbleball and Ardingly reservoirs, respectively, with forecasts for Ardingly now extending into next year. Water companies are also exploring water transfers from other areas to mitigate shortages, although concerns persist about Venford reservoir in Devon, where disruptions are considered more imminent. Monitoring has also begun for Cornwall’s Stithians and Drift reservoirs.
The government’s Scientific Advisory Group for Emergencies (Sage) has been involved in reviewing water companies’ modeling of water-saving measures to safeguard supplies. Officials have underscored that normal autumn and winter rainfall would be insufficient to fully recover from the drought, estimating that 120 percent of average long-term rainfall over the next six months would be required for a nationwide rebound. The drought has also expanded recently to encompass Yorkshire.
In response, Dame Angela Eagle directed the Environment Agency to prioritize protecting public water supplies by restricting releases from reservoirs into rivers, aiming to reduce interruptions to supply. However, internal concerns have been raised about the environmental impact of such measures, particularly risks to fish populations from lowered water levels and diminished water quality.
The government affirmed that customer water supplies remain uninterrupted, emphasizing actions to redistribute water supplies, accelerate leak detection, and monitor reservoir and river levels daily. South West Water stated it does not anticipate imposing water restrictions early next month and is taking urgent steps to protect supplies. South East Water also confirmed that it is not considering a "day zero" scenario for 2027 following recent interventions. Southern Water and EDF Energy, responsible for Hinkley Point C, declined to comment on the situation.