Sewerage connections for new housing developments (England)

This article provides information about water and sewerage services for proposed and new housing developments. It covers planning permission, regulations for new builds and options for drainage connections, and what constituents can do if they are concerned about a drainage connection.

Planning, building regulations, and water are devolved, and the below information applies to England.

What are sewerage connections?

Sewerage connections remove sewage and wastewater from properties.

Most new properties are connected to two sewers:

• A foul sewer, which removes sewage to the main public sewer for treatment.
• A surface water sewer, which removes rainwater runoff to a rainwater sewer or local river.

Some properties may be connected to combined sewers (removing both sewage and rainwater). This is more common for properties which are older.

Drainage can be delivered either through the public sewer system or privately. There is a statutory duty for water companies to provide and maintain an adequate sewer network.

What impacts can new developments have on sewerage?

New developments increase pressure on the public sewer system because they increase the number of users. They also reduce the ability of the ground to naturally absorb rainwater (because they involve creating more hard surfaces) and thereby increase the amount of water entering the sewers.

Planning for sewerage connections What is the role of water companies in ensuring sufficient sewerage infrastructure is available?

Water companies are legally required to provide water and sewerage services to new developments within the region they serve. In practice, this means that new developers have a right to connect their drains to the main sewers operated by water companies.

Water companies have a duty to maintain the water supply system. Part of this includes planning ahead to ensure that demand for water services does not outstrip supply. They must prepare long-term Water Resources Management Plans (WRMPs) that consider future housing demand and population growth. More information is set out in the Library briefing on Future water resources.

Water companies, sewerage undertakers, and local planning authorities are expected to work together to ensure that “investment plans of water and sewerage companies align with development needs.” This provides reassurance to local planning authorities that there will be sufficient water and sewerage capacity for the number of new homes in their local plan.

Understanding what infrastructure is needed and where is a key part of the local plan process. Therefore, it is good practice for local planning authorities to engage with water companies operating in their area as part of the local plan process. This helps local authorities to understand existing infrastructure capacity, future investment plans, and how this aligns with housing and other growth proposed in local plans.

Government guidance also requires water companies to engage with local planning authorities so their investment plans take account of local development needs.

Are sewerage connections considered in the planning process?

Building a new housing development will require planning permission from the local planning authority. A local planning authority will generally decide planning applications in line with its local plan, a document setting out its policies for future development of its area.

It is for the local planning authority to decide whether the capacity of wastewater infrastructure is a relevant consideration to a specific planning application. This will depend on the circumstances of each application.

The government’s National Planning Policy Framework (NPPF) says local planning authorities should include policies in their local plan to make “sufficient provision” for sewerage infrastructure (see NPPF paragraph 20b). When deciding planning applications for new developments, it says local planning authorities should consider “the availability and capacity of infrastructure…both existing and proposed – as well as their potential for further improvement” (see NPPF paragraph 129c).

What can a planning authority do if sewerage infrastructure is not sufficient for proposed developments?

Developers may need to provide information to the local planning authority as part of their planning application on how they will deal with sewage from new developments.

A local planning authority will not necessarily refuse planning permission for new developments if it is concerned about the capacity of wastewater infrastructure. To address concerns, a local planning authority could grant planning permission subject to conditions. For example, planning conditions might require that the development is not occupied until mitigation measures relating to sewerage have been implemented.

A local planning authority could also negotiate an agreement with a developer that requires them to upgrade sewerage infrastructure. The NPPF states that a local plan should set out the contributions expected from development, including infrastructure needed for flood and water management (see NPPF paragraph 35).

Are water and sewerage companies consulted about planning applications?

Local planning authorities are not legally required to consult water and sewerage companies, as they are not statutory consultees. The government encourages local planning authorities to engage with water and sewerage companies to determine whether they need to consider sewerage issues in a planning application.

A local planning authority would also consult a water company on a draft local plan or draft Local Development Order where the current operations and strategic plans of the water company are likely to be affected.

Putting new sewerage connections in place

For new developments, the developer is usually responsible for connecting a new building to drains and public sewers (or another sewerage system, such as a septic tank). They will pay a water company to construct the infrastructure or may choose to lay the infrastructure themselves (through an accredited self-lay company).

Sewage drainage

Schedule 1 Part H of the Building Regulations 2010, which set out how new homes should be built, require new buildings to have an“adequate system of drainage” to carry sewage to a public sewer (or to a private sewer that connects to a public one). Where this is not possible, new buildings could have a cesspool, private wastewater treatment system, or septic tank.

It is the responsibility of the developer or building owner to either provide a drainage system or ensure any connections to the public sewer system meet the standards of water and sewerage companies.

Rainwater drainage

Building regulations require paved areas around new buildings to be built so they can be “adequately drained”. They say that rainwater should drain into a system that allows water to drain into the surrounding soil, such as a soakaway (a pit in the ground that collects water, which then drains gradually into the soil). Where this is not possible, rainwater should drain to a watercourse or a sewer.

Although building regulations encourage drainage into the soil, they permit developers to connect surface water drainage into public sewers. Connecting surface water drainage into combined sewers is common practice across England. This has led to concerns that new developments increase surface and sewer flooding risks by creating hard surfaces that prevent surface water soaking away gradually.

Sustainable drainage

Sustainable drainage systems (SuDS) use natural drainage management techniques including grassed areas, soakaways, and wetlands to reduce the risk of surface water flooding.

The government advises that major developments, for example those where at least ten new homes are built, and developments in areas at risk of flooding should have SuDS “unless there is clear evidence that this would be inappropriate” (see NPPF paragraphs 181c and 182). However this is not a legal requirement.

What is the process for connecting a new development to the public sewer?

It is the responsibility of the property owner to connect or organise proper connection to the main public sewer. For a new building, the property owner will usually be the developer.

Property owners may pay the local water and sewerage company to lay the infrastructure required to connect to a public sewer, or they may choose to self-lay the infrastructure required. Water companies are responsible for ensuring that any new sewers are built to meet the water industry code for adoption.

What happens after the development has been connected?

Once a mains drainage connection to a public sewer is in place, the water company generally ‘adopts’ any drains connecting multiple properties to the sewer (called ‘lateral drains’). These drains then become the responsibility of the water company.

The drains that fall within a property boundary or connect the individual property to lateral drains remain the responsibility of the property owner.

Ofwat, the water regulator, has published a diagram illustrating responsibilities for water pipes, and Citizens Advice sets out who is responsible for repairs and maintenance.

Who is responsible for issues with sewerage connections?

Constituents who believe that their sewerage system has been poorly constructed may wish to contact their local authority. Local authorities can require a builder or developer to fix non-compliant building work.

If wastewater pipes for sewage are connected to a sewer intended for rainwater only, this can cause pollution and is known as a misconnection. The water company may be able to help identify this.

Correcting a misconnection is the responsibility of the property owner. In the case of new developments, developers remain responsible owners of drainage pipes until they are adopted by the relevant water company.