Defra has approved an ordinary drought order for South East Water covering the River Ouse and Shell Brook in Sussex, effective from 3 December 2025 until midnight on 2 June 2026. The decision follows an exceptional shortage of rain and a judged risk to public water supplies in the company’s Sussex zone.

The order adjusts how much water must be left in local watercourses and when abstraction is allowed. Augmentation and compensation releases from Ardingly Reservoir into the Shell Brook drop from 4,000 cubic metres per day to 1,000 cubic metres per day-equivalent to a reduction from 4 to 1 megalitre per day. The aim is to conserve storage while keeping a baseline flow in the brook.

For abstraction at Barcombe Mills on the River Ouse, the hands‑off flow threshold falls from 20 to 15 megalitres per day, with a further reduction to 10 megalitres per day if Ardingly Reservoir slips below 45.7 metres Above Ordnance Datum, which equates to usable storage under 500 megalitres. The order also raises permitted takes once natural flow is above 40 megalitres per day.

Technically important changes include shifting the point at which the maximum licensed daily abstraction of 90.2 megalitres is reached: from natural flow over 196 megalitres per day to over 184.89, or over 173.78 if the reservoir trigger is met. In addition, abstraction permitted under Schedule 4 of the licence may run for the whole period the drought order is in force rather than only from November to April.

Stronger oversight is built in. South East Water must carry out the environmental monitoring plan set out in section 5.4 of its Environmental Assessment Report (Johns Associates, October 2025), file weekly results with the Environment Agency, and immediately notify and implement agreed mitigation if indicators in Table 5.2 point to stress on the river. The Agency can require changes to the plan at any time.

While November’s rain has improved conditions in many places, Sussex remains fragile. The Environment Agency reported Ardingly Reservoir at 38.3% on 17 November and around 40% by 25 November, still well below where it needs to be heading into winter. England’s reservoir stocks were 77% at 25 November, and south‑east England saw about 85% of average November rain, with the Met Office noting a clear north–south split this autumn.

This order caps a sequence of drought actions. South East Water has had a hosepipe ban in parts of Kent and Sussex since 18 July, secured a winter drought permit on 22 September to lower Shell Brook compensation flows, and applied on 10 October for the River Ouse drought order. It also sought a non‑essential use order for some businesses on 24 October as a contingency.

The legal guard‑rail is explicit: nothing in the order authorises environmental damage under the Environmental Damage (Prevention and Remediation) (England) Regulations 2015. With lower augmentation and compensation flows, the monitoring and rapid‑mitigation duties are the safety net for river life as winter recharge unfolds.

Residents and businesses can help ease pressure now. The Environment Agency warns that, without sustained winter rainfall, drought is likely to persist into 2026. Using less water through winter speeds reservoir recovery and reduces the need to keep emergency measures in place. Shorter showers, fixing leaky loos and holding off on non‑essential outdoor use are small steps that add up.

Documents underpinning the decision-the abstraction licence and the Environmental Assessment Report-are available to inspect by appointment via the Environment Agency at Teville Gate House in Worthing. The company must keep detailed records and provide weekly reports to the Agency showing compliance and how sources have been operated.

Longer term, Sussex needs a sturdier mix of solutions: faster leakage reduction, smart metering, water reuse and catchment restoration to keep more water in rivers during dry spells. The National Drought Group has already asked water companies to keep up winter‑season water‑saving and asset readiness; today’s order is a necessary bridge, not the destination.