UK statutory guidance for water and sewerage companies under section 94 of the Water Industry Act 1991. DWMPs are 25-year strategic plans produced on a 5-year cycle, structured around Strategic and Tactical Planning Units (sub-catchment and wastewater treatment works level). They require climate projections, CSO frequency analysis, WFD linkage and adaptive planning under uncertainty — making them the nearest real-world equivalent to an IUWMP.
DEFRA; ENVIRONMENT AGENCY; OFWAT; WELSH GOVERNMENT & NATURAL RESOURCES WALES (2025): Guidelines for Statutory Drainage and Wastewater Management Plans (DWMPs). London: gov.uk-Environment-Water Management. URL [Accessed: 30.04.2026]