Drainage and utilities infrastructure compliance

Drainage infrastructure on new developments must comply with several regulatory frameworks simultaneously:

• Building Regulations (Approved Document H) set the technical standards for foul drainage, wastewater treatment, rainwater drainage, building over sewers, and separate drainage systems
• Water Industry Act 1991 governs your right to connect to public sewers (Section 106) and the process for having new sewers adopted by the water company (Section 104)
• Flood and Water Management Act 2010 establishes SuDS (sustainable drainage systems) requirements, which are mandatory in Wales and increasingly expected in England through planning conditions
• Health and safety legislation imposes specific duties for confined spaces work and utility trenching
• Environmental Permitting Regulations require permits for discharging water to rivers, streams, or groundwater during construction

The following steps take you through each area in the order you will typically encounter them during a development project.

Approved Document H of the Building Regulations sets out the performance standards your drainage system must achieve. It covers five areas: foul drainage (H1), wastewater treatment systems and cesspools (H2), rainwater drainage (H3), building over sewers (H4), and separate systems of drainage (H5).

Your drainage design must satisfy Building Control, and if you intend the sewers to be adopted by the water company, it must also meet the water company's Design and Construction Guidance (formerly Sewers for Adoption).

Sustainable drainage systems (SuDS) manage surface water runoff by mimicking natural drainage processes. They reduce flood risk, improve water quality, and create biodiversity and amenity value. The regulatory approach to SuDS differs significantly between England and Wales.

If your development includes new sewers serving multiple properties, you will need a Section 104 adoption agreement with the water company. This commits the water company to adopt the sewers after construction to the required standard and a maintenance period. Without it, the sewers remain private, which causes problems for property sales and mortgage lending.

Drainage and utility work frequently involves entering confined spaces such as manholes, sewers, inspection chambers, and service ducts. It also involves excavating trenches where underground services may be present. Both activities carry serious risks including fatal injury, and are subject to strict regulatory requirements.

Construction activities that discharge water to rivers, streams, or groundwater require an environmental permit from the Environment Agency (England) or Natural Resources Wales. This includes dewatering excavations and discharging treated site runoff. Unauthorised discharge is a criminal offence with unlimited fines.