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Planning your sewerage infrastructure — considerations for Housebuilders

Sewerage infrastructure, and in particular surface water drainage, can present challenges for developers.

Housebuilders and developers will be familiar with the range of infrastructure that must be installed in order to provide utility services to new-build premises, including water, electricity, gas, telecommunications and sewerage (both foul and surface water). Sewerage infrastructure, and in particular surface water drainage, can present challenges for developers, particularly as multiple agencies and landowners will need to be interacted with.

Our energy and utilities team have the necessary expertise of water law, gained through many years of working in and with the water sector, to help guide developers through these challenges. Below we outline some of the interactions, in respect of sewerage issues, that developers will face when they take on a new build project.

A developer, to secure provision of sewerage infrastructure, may have to consider requisitioning, especially in relation to lengths of sewer that will require construction outside land in the developer’s control.

In respect of sewerage infrastructure to be laid by a developer, an adoption agreement will typically need to be completed with the incumbent sewerage undertaker, to secure that the pipework will become vested in the undertaker following satisfactory construction and expiry of a defects liability period.

When the necessary sewers, lateral drains and drains have been laid, connections to the public sewerage system, particularly for foul drainage, may be necessary. Subject to specific exceptions, rights of connection are available for drainage for domestic purposes.

Planning authorities will look to secure that surface water disposal is achieved wherever possible through a sustainable drainage system. In addition, the lead local flood authority, as a statutory consultee, will seek to insist on a system that is as risk-free as possible from a flooding perspective.

The hierarchy of sustainable drainage solutions favours ground infiltration as a preferred option. If this is not possible then discharge to a watercourse or discharge to a surface water sewer should be considered, in that order. Discharge to a combined sewer is very much a last alternative.

Where surface water is to be discharged to a nearby watercourse, of whatever size, a number of prerequisites will typically come into play. These include the possible need for a discharge consent, a flood defence consent, land drainage consent, and the consent of the riparian landowner.

Rights of connection to existing public sewers may be complicated by ongoing uncertainties over the full extent of the public network as a consequence of the 2011 statutory scheme for transfer of private sewers and lateral drains (and pumping stations in 2016). Consequently, search results from the commercial equivalents of CON29DW may not accurately reveal existing statutory assets in all cases.