London Borough drainage requirements

London Borough drainage requirements describe the supplementary local policies, technical guidance and planning conditions imposed by individual London boroughs in addition to UK Building Regulations and Thames Water requirements. Each of the 32 London boroughs and the City of London publishes its own local development management policies, often informed by the London Plan and the borough's role as the lead local flood authority. Common additional requirements include the SuDS drainage hierarchy, attenuation rates for new development, pre-treatment of surface water before discharge and conservation area considerations. Practical implications for homeowners include checking the borough's local plan and planning portal before submitting an application that involves drainage, and engaging early with the borough drainage engineer where attenuation or build-over consent may be needed. Practitioners regularly cross-reference borough policy with Building Regulations Part H3 and Thames Water consenting practice.