South East Water drought order for Ouse starts 3 Dec
If you live or study in Sussex, you’ll hear a lot this winter about “drought orders”. From Wednesday 3 December 2025, South East Water will operate under a new ordinary drought order for the River Ouse and Shell Brook after the Secretary of State confirmed an exceptional shortage of rain and risks to public water supply. By law, ordinary drought orders run for up to six months; this one is scheduled to end on Tuesday 2 June 2026, with the legal six‑month cap set out in the Water Resources Act 1991. According to legislation published on legislation.gov.uk, the order temporarily changes how the company takes and releases water to balance drinking water needs with river health.
In simple terms, the order lowers the minimum river flow-known as the hands‑off flow-required before South East Water can abstract at Barcombe Mills. In normal conditions the company must leave at least 20 megalitres per day (ML/d) in the Lower Ouse below the abstraction point. During the order the threshold drops to 15 ML/d and, if needed, to 10 ML/d in tougher conditions. South East Water has set out these figures in its public guidance for the River Ouse application.
A quick definition for your notes: hands‑off flow is the regulatory floor-if the river is below that flow, abstraction must pause. Lowering it gives the operator more flexibility to keep taps running, but it also means less water moving through habitats used by fish, insects and plants. That’s why drought orders are time‑limited and paired with strict monitoring by the Environment Agency and independent ecologists.
The order also adjusts “compensation” and “augmentation” releases from Ardingly Reservoir into the Shell Brook. These are the steady top‑up flows that mimic what the stream would have received without the dam. For this winter period, the minimum release is reduced from 4 ML/d to 1 ML/d, matching the approach already authorised under the Ardingly winter drought permit granted on 22 September 2025. The Gazette notice and South East Water’s materials confirm this 4 ML/d to 1 ML/d change.
There’s a trigger written into the order for when storage gets critically low. If Ardingly Reservoir drops below 45.7 metres Above Ordnance Datum-equivalent to under 500 megalitres of usable storage-the stricter 10 ML/d hands‑off flow applies until levels recover. Think of this as a safety brake: it stretches supplies across winter refill while keeping a baseline flow moving through the Ouse to support wildlife and water quality.
The order also reshapes how much can be taken when the river is healthier. Once natural flow on the Ouse rises above 40 ML/d, the licensed abstraction volumes step up more quickly than before. The company’s daily ceiling of 90.2 ML/d is now reached at a slightly lower river flow than under the standard licence, so more water is moved on good‑flow days and less on poor‑flow days. These details are set out in the order’s explanatory note on legislation.gov.uk and are designed to concentrate abstraction when the river can better cope.
None of this is a free pass. The order requires South East Water to run an agreed environmental monitoring plan, keep it under review with the Environment Agency, and file weekly reports showing monitoring results, how sources were operated and what mitigations-such as local aeration or fish rescue-were used if warning thresholds were met. The monitoring framework is drawn from the Environmental Assessment Report (Johns Associates, October 2025) and can be tightened by the Agency at any time.
An important legal point for your coursework: the order explicitly states that it does not authorise environmental damage. That matters because regulation 19 of the Environmental Damage (Prevention and Remediation) (England) Regulations 2015 sets out when operators may appeal liability; drought orders are not a shield if harm occurs. In other words, enforcement remains on the table should damage be shown.
What does this change for you at home? This type of order alters how water is moved in the system; it doesn’t directly set household restrictions. South East Water’s separate temporary use ban (hosepipe ban) for parts of Kent and Sussex remains the reference for customers, with exemptions in Sussex removed on 17 October 2025. The company has also applied for a non‑essential use order for some business activities if conditions worsen. These steps-and the Ouse drought order-are tracked in the Environment Agency’s weekly drought summaries.
Why now? Despite some wetter weeks in November, Ardingly Reservoir remains behind seasonal norms. The Environment Agency reported storage had risen to about 40% by 25 November 2025-an improvement, but still low for late autumn-so banking winter rainfall and reducing drawdown remains a priority. This winter order aims to boost the chances of a healthier starting point for summer 2026.
A short glossary you can teach with: a megalitre is one million litres. Hands‑off flow is the minimum that must remain in the river before any water can be taken. A compensation release is a steady flow from a reservoir to make up for a dam interrupting a stream. An augmentation release is an extra pulse to support a downstream target during dry spells.
If you’re studying policy or planning a field visit, you can inspect the abstraction licence and the Environmental Assessment Report in person at Teville Gate House in Worthing by appointment with the Environment Agency. South East Water also hosts the public notice and statement of reasons for this order on its website, which provide helpful context on the Sussex drought and the company’s modelling.
Finally, remember the time limits. Ordinary drought orders last up to six months and can only be extended-by a formal amendment-up to a one‑year maximum from the start date. This order is due to end at midnight on 2 June 2026 unless Defra changes it. For students of water law, section 74 of the Water Resources Act is the anchor you’ll return to again and again.