Portsmouth Water has released its Draft Drought Plan 2027, setting out how the company will manage water supplies through escalating drought conditions in one of England's most water-stressed regions. The timing is notable: according to the Environment Agency's national water situation report for April 2026, south-east England recorded its driest April since 2011, with the region receiving just 16% of its long-term average rainfall, and soil moisture deficits across the area well above what would be expected for the time of year.
The publication is part of a sector-wide regulatory cycle in which all English water utilities are required to update their drought plans every five years in line with Environment Agency guidelines. Portsmouth Water submitted its draft to Defra earlier this year, with public consultation now running until 14 August 2026 and the final plan expected in spring 2027.
Every drop of Portsmouth Water's supply originates from the chalk aquifer, either directly through boreholes and springs or via the groundwater-fed River Itchen
Portsmouth Water covers around 740,000 customers across Hampshire and West Sussex, served entirely from chalk groundwater sources, making the company uniquely dependent on winter rainfall and aquifer recharge. The plan establishes a five-tier trigger framework, driven by groundwater levels at a single formal monitoring point for the entire supply area, with demand and supply-side actions escalating as conditions worsen. Early interventions focus on enhanced leakage control and pressure management, progressing through temporary restrictions on household and commercial water use. Only one supply-side drought permit option is identified, allowing a temporary increase in abstraction beyond normal licensed limits at one key groundwater source.
As drought severity increases, the plan introduces a further tier of response before emergency measures become necessary. These options, referred to internally as "More Before 4", involve temporary pump upgrades or depth adjustments at multiple groundwater sources to extract additional yield as water levels continue to fall, buying time before the most severe Level 4 restrictions, such as standpipes and rota cuts, become necessary. Options previously included in the 2022 plan, including sea tankering and temporary desalination, have been formally removed as impractical, though transferred to the company's emergency plan for consideration.
The plan also reflects a material revision to the volumes Portsmouth Water supplies to neighbouring Southern Water under bulk supply agreements. The amount committed under critical drought conditions has been stepped down from 30 Ml/d to 15 Ml/d for the current period, rising incrementally back to 30 Ml/d by 2029-30, following joint modelling and a shared operational understanding agreed in December 2025. Much of this supply originates from the River Itchen, a protected chalk stream subject to strict environmental flow constraints and ongoing joint investigations into abstraction impacts on designated habitats.
The plan is supported by both a Strategic Environmental Assessment and a Habitats Regulations Assessment, reflecting the environmental sensitivity of a supply area that includes internationally protected habitats across a chalk landscape.
