Real Estate Blog: Surface Water Drainage – matters for developers to consider at site acquisition stage

A development site’s surface water drainage solution may appear straight forward on paper. For example, there may be an existing combined or surface water sewer on, or close to, the site, or a ditch or watercourse nearby or running through or abutting the site. However, developers need to ensure that sufficient due diligence is carried out at an early stage, to ensure that surface water can be discharged from the site via the preferred solution.

Even if there is an existing combined or surface water sewer within or near to the site, the sewerage undertaker may refuse to permit a surface water discharge connection if that connection would be prejudicial to the undertaker’s sewerage system. The overloading of existing drainage systems presents an ever-increasing problem for developers and often alternatives to mains surface water drainage need to be considered.

If a ditch or watercourse is not fully within the site boundary, the first port of call is to check whether the title to the site benefits from a legal easement to drain surface water into such ditch or watercourse. If it does, then the next step is to consider whether the right as granted is sufficient to serve the proposed development.

If the site does not benefit from a legal drainage easement, then the availability of prescriptive rights (rights acquired by long user) or riparian rights (rights enjoyed by the owner of land adjoining a natural watercourse) may need to be considered.

If the proposed development would lead to an intensification of use beyond that originally intended at the time of grant or commencement (i.e. due to a higher run off rate), then such use will not be permitted, and the easement cannot be relied upon.

It is important for developers to also consider whether it will need the on-site surface water infrastructure to be adopted by the sewerage undertaker. If it does, then further consideration needs to be given to whether the sewerage undertaker will be satisfied with the rights that the developer seeks to rely on.

Ordinarily a sewerage undertaker wants to be able to directly benefit from a right to discharge surface water through the entire system. In practice this can be difficult to satisfy if parts of the system cross third-party land without the grant of easements from the third-party landowner to the sewerage undertaker.

Developers also need to be aware of the government’s recent announcement that it intends to implement Schedule 3 to the Flood and Water Management Act 2010 to mandate sustainable drainage (SuDS) in new developments in England from 2024. This will mean that a separate application for the approval of SuDS will need to be made to the SuDS Approving Body (SAB) in addition to the usual planning application for the proposed development. The SAB may approve the SuDS subject to conditions and may require a non-performance bond. Any contracts or options for the purchase of development sites should therefore be drafted with these new requirements in mind.

If you would like any further advice on this topic, please get in touch with Julia Lock from our Housebuilding and Strategic Land team.