Building the evidence base for regional water planning

Authors: Professor Ana Mijic, Dr Eduardo Rico Carranza and Jennifer Bird, Campaign Manager, Grantham Institute

The UK Government published a white paper on water reform (‘A New Vision for Water’) in January 2026, which contains plans to reform the approach to water planning, reducing the current complex system down to two core planning frameworks: one for water supply and one for water environment.

In addition, the Government intends to introduce a new regional water planning function, which will address the “missing middle” governance gap. 

This briefing explores the case for taking a more holistic approach to water planning and proposes some concrete steps towards making that a reality. More specifically, while holistic approaches can encompass many important dimensions, including stakeholder engagement, water governance, institutional coordination and decision-making processes, this briefing focuses on the evidence needed to support proposed regional water planning.

Key points

• Taking a systems approach to water management enables decision-makers to design policies that reflect how water infrastructure and natural systems operate in practice, delivering savings for consumers and farmers while achieving measurable improvements in environmental outcomes.

• Regional water planning requires an evidence base that supports systems-based decision making. This includes:

  1. agreeing on a consistent set of water system baseline indicators, and
  2. using integrated modelling approaches capable of representing interactions between natural and engineered systems across both urban and rural areas.

• Recent advances in integrated modelling mean that these approaches can now support policies addressing multiple aspects of water management simultaneously, allowing interventions to be assessed across the whole water system rather than in isolation.

• The examples presented in this briefing demonstrate how streamlined indicators and integrated models can provide new insights for decision making, for example, by identifying lower-cost pathways for pollution reduction across rural and urban sources, assessing the cumulative impact of new housing development, and revealing co-benefits and trade-offs between water supply, flood risk, and environmental objectives.

• The move to regional water planning provides an opportunity to test and refine approaches to evidence creation for water management. Regulators, water companies, local authorities, catchment partnerships, and researchers should work together to develop evidence that is transparent, comparable across regions, and capable of supporting robust decision-making under future uncertainty.