This information should not be relied upon as legal or professional advice. Read the disclaimer.

This casework 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 this article 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).

Drainage can be delivered either through the public sewer system or privately.

What impacts can new developments have on sewerage?

New developments can 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 water entering the sewers.

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 says that local planning authorities should include policies in their local plan to make “sufficient provision” for sewerage infrastructure. When deciding planning applications for new developments, it says local planning authorities should consider “the availability and capacity of infrastructure” (PDF).

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

Developers may need to provide information 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.

Are water and sewerage companies consulted about planning applications?

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. However, local planning authorities are not legally required to consult water and sewerage companies.

The government has said it will consult on whether to make water and sewerage companies ‘statutory consultees’ in the planning process. In January 2024, the government said it will publish a consultation “later this year”.

What is the process for putting in place sewerage connections?

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 or sewerage company to construct the infrastructure, or may choose to lay the infrastructure themselves (through an accredited self-lay organisation).

Once the infrastructure is complete, the parts of drains that carry sewage and rainwater for multiple properties are usually adopted by the local water company, which becomes responsible for maintaining them. Parts of drains that carry wastewater only for one property become the responsibility of the property owner.

Sewage drainage

Building regulations, which set out how new homes should be built, require new buildings to have an “adequate system of drainage” to carry foul water (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.

In 2024, the government plans to make it a legal requirement for new developments to connect to sustainable drainage systems (SuDS). SuDS use natural drainage management techniques including grassed areas, soakaways, and wetlands to reduce the risk of surface water flooding.

The government already advises that major developments, for example those where at least 10 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” (PDF). However, this guidance is not legally binding. The government has said that making SuDS a legal requirement for all new developments will reduce overall risks of flooding and pollution, protecting homeowners and the environment.

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 (through an accredited self-lay provider). 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.

About the authors: Felicia Rankl and Nuala Burnett are researchers at the House of Commons Library, specialising in planning and water respectively.


The Commons Library does not intend the information in this article to address the specific circumstances of any particular individual. We have published it to support the work of MPs. You should not rely upon it as legal or professional advice, or as a substitute for it. We do not accept any liability whatsoever for any errors, omissions or misstatements contained herein. You should consult a suitably qualified professional if you require specific advice or information. Read our briefing for information about sources of legal advice and help.

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