Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, what guidance her Department provides to water companies and planning authorities on determining when sewage treatment works have sufficient capacity to accommodate additional development.

Water companies are under a statutory duty to provide new water and sewerage connections to residential properties, as well as planning to meet the needs of growth as part of statutory Water Resources Management Plans, and Drainage and Wastewater Management Plans (DWMPs). The decision on whether to approve a development lies with the relevant Local Planning Authority, in line with guidance such as the National Planning Policy Framework. Sewerage undertakers must ensure that they have planned infrastructure need to meet both existing demand, and planned levels of household and non-household growth, as informed by local development plans and relevant modelling. In May 2025, Defra published guidance for the next round of DWMPs instructing sewerage undertakers on how they should prepare their statutory plans, setting out how they intend to manage and develop their infrastructure to meet current and future demand.