What is a Section 106 (drainage)? The right to connect to a public sewer

A Section 106 sewer connection is the statutory right, under section 106 of the Water Industry Act 1991, for the owner or occupier of a property to connect its drains to the public sewer. It is a right rather than a favour: the sewerage undertaker cannot simply refuse it because the network is busy. That single principle shapes how thousands of new homes and commercial buildings reach the public sewer each year, and it is routinely confused with the unrelated planning obligation that shares the same number.

Getting the foul route confirmed early is often the difference between a smooth start on site and a stalled one, which is why we deal with it head-on when we prepare a foul drainage strategy for planning. This guide sets out what the drainage Section 106 covers, what you can and cannot connect, the narrow grounds on which a water company may say no, and how the right sits alongside sewer adoption, building control and the surface water rules now bearing down on it.

The right to connect is one of the oldest and strongest entitlements in English water law, and in 2026 it is also one of the most contested.

What is a Section 106 sewer connection?

A Section 106 sewer connection is the legal right of an owner or occupier to make their drain or private sewer communicate with the public sewer, so that foul or surface water can discharge into the public system. It attaches to the property, not the person, and it passes with the land when the property is sold.

To see where the right applies, it helps to picture the drainage chain from the building to the main:

• The private drain or sewer carries flow from the building to the boundary and is the property owner's responsibility.
• The lateral drain runs from the boundary to the public sewer and is usually the water company's responsibility once vested.
• The public sewer is the adopted main into which the connection is ultimately made, maintained by the sewerage undertaker.

Section 106 governs the moment of connection between that private pipework and the public sewer. It does not, on its own, make the pipe adoptable, and it is separate from the distinction between foul, surface and combined sewers that decides which public sewer a given flow is even allowed to enter.

Section 106 for drainage is not the same as a planning Section 106

Two entirely different laws share the label "Section 106", and developers conflate them constantly. The drainage Section 106 is a water-industry right to connect. The planning Section 106 is a legal agreement between a developer and a council that secures contributions or obligations as part of a planning permission. They come from different Acts, are granted by different bodies, and do different jobs.

If someone on a project says "we've got the Section 106 sorted", it is always worth asking which one they mean. A planning agreement being signed tells you nothing about whether the sewerage undertaker has accepted the connection, and vice versa.

What you can and cannot connect

The right in section 106(1) of the Water Industry Act 1991 is broad, but section 106(2) carves out important exclusions. You cannot use the right to discharge anything the public sewer is not built to take, or to force the wrong kind of flow into the wrong kind of sewer. The statutory wording is the anchor for everything that follows:

The exclusions matter as much as the right. You cannot connect so as to discharge certain trade effluent through the right to connect, make an unlawful discharge, send foul water into a sewer provided for surface water only, or send surface water into a sewer provided for foul only. Nor can you connect a drain or sewer directly to a storm-water overflow sewer. Where a development mixes flows or sits near the wrong class of sewer, confirming which public sewer is lawfully available is part of the surface water drainage strategy or the foul strategy, not an afterthought at connection stage.

When can a water company refuse a Section 106 connection?

A sewerage undertaker can refuse a connection only on narrow grounds, and it must do so within 21 days of the connection notice. Section 106(4) lets it refuse where the manner of construction or condition of the drain or sewer does not meet its standards, or where making the connection would be prejudicial to its sewerage system. Silence past the deadline is not neutral: if the undertaker does not serve a valid refusal within the window, the connection may proceed.

The water company has 21 days from the connection notice to refuse, and it can refuse only on construction, condition or system-prejudice grounds. A network short of capacity is not one of them.

That last point is the one developers most often get wrong, and the one water companies have most often tried to stretch. The grounds are limited to:

• Construction or condition: the drain or sewer is not built or maintained to a standard the undertaker can reasonably accept.
• Prejudice to the system: the specific connection, as proposed, would harm the operation of the sewerage network.

Lack of headroom in the network, on its own, is not a lawful reason to refuse, redirect or delay a connection. If a water company is raising capacity as an obstacle, it is worth understanding how water companies engage with the planning process before accepting the position.

Barratt Homes v Welsh Water: the case that fixed the right to connect

The scope of the right was settled at the highest level in Barratt Homes Ltd v Dŵr Cymru Cyfyngedig (Welsh Water) [2009] UKSC 13. Welsh Water had tried to insist that a developer connect at a point of the undertaker's choosing, further away, to protect its network, rather than at the nearer point the developer had selected. The Supreme Court disagreed.

By a majority of four to one, the court held that the developer, not the undertaker, chooses the point of connection, and that inadequate capacity in the existing sewer cannot be used to refuse or reroute a connection made under Section 106. The undertaker's remedy for a network that cannot cope is to improve the network, not to turn away a lawful connection. The ruling has governed the right to connect ever since, and it is why "the sewer is full" has never been a complete answer to a Section 106 notice.

In Barratt Homes v Welsh Water, the Supreme Court confirmed by a 4–1 majority that the developer chooses the connection point and that a lack of sewer capacity cannot justify refusing a Section 106 connection.

Connecting is not the same as adopting: Section 106 versus Sections 104 and 102

Connecting a drain under Section 106 is a different act from having a sewer adopted so the water company maintains it long-term. New estate sewers are usually built to an adoptable standard and then vested in the undertaker, either by a Section 104 agreement negotiated in advance of construction or, less commonly, by a Section 102 adoption of an existing sewer. Section 106 is about the flow being allowed in; Sections 104 and 102 are about who owns and maintains the pipe afterwards.

On most developments you need both, and in the right order. Our guide to Section 104 and Section 102 sewer adoption agreements covers the adoption side in full; this page stays with the right to connect.

How to apply for a Section 106 sewer connection

The process is a defined sequence, and it rewards starting early because the statutory clock and the infrastructure paperwork run on their own timetables. In practice it runs like this:

1. Confirm the point of connection. Identify the public sewer, its type (foul, surface or combined), and a realistic connection point. As a rule of thumb, a mains connection is expected where a public sewer sits within about 30 metres per property served.
2. Serve the Section 106 connection notice. Give the sewerage undertaker formal notice of the proposed connection, with the details it needs to assess construction, condition and system effect.
3. Allow the 21-day period. The undertaker has 21 days to refuse on valid grounds. If no valid refusal is served, the connection can proceed.
4. Pay the infrastructure charge. A standard infrastructure charge is normally payable per connection to reflect the load added to the wider network.
5. Connect under supervision. Make the physical connection to the undertaker's requirements, which may mean the undertaker carrying out or supervising the work, and may require a street works licence if the connection is made in the highway.

Surface water, SuDS and the future of the right to connect

The right to connect surface water to the public sewer is being squeezed from two directions, and this is where the law is moving fastest in 2026. First, the 2025 National Standards for Sustainable Drainage Systems, published by the Government, put the public sewer at the bottom of a discharge hierarchy: reuse first, then infiltration, then a watercourse, and only then the sewer as a last resort. A planning drainage strategy now has to justify why surface water is going to the sewer at all, rather than treating the sewer as the default.

Under the 2025 National Standards, the surface water discharge hierarchy runs reuse, then infiltration, then a watercourse, then a surface water sewer, with a combined sewer only as the last resort. Cost alone never justifies skipping a tier.

Second, the near-automatic right to connect is itself under formal review. The Independent Water Commission, led by Sir Jon Cunliffe, reported its concerns about new development adding unplanned load to the network. The Government's January 2026 water white paper, A new vision for water, then confirmed that ministers are working with the housing department to review the right to connect to both water supply and the sewerage system. The direction of travel is that the current near-automatic entitlement may become conditional on capacity being available. Wales has already gone further: since Schedule 3 of the Flood and Water Management Act 2010 was commenced there, the right to connect surface water is conditional on a sustainable drainage system being approved. England has not commenced Schedule 3, so for now the Barratt Homes position still holds. It is no longer safe to assume it always will.

For any scheme relying on a sewer connection for surface water, that makes early, evidenced drainage design a matter of programme risk as much as compliance. The safest route is to build the discharge hierarchy into the drainage strategy from the outset.

Three separate regimes: planning, connection and building control

A recurring cause of delay is treating planning permission as if it also authorises the sewer connection. It does not. Three separate consents govern getting drainage built and connected, and clearing one does not clear the others:

• Planning permission decides whether the development, including its drainage strategy, is acceptable in land-use terms.
• The Section 106 connection is the water-industry right to physically connect to the public sewer.
• Building control (Approved Document H) governs the technical standard of the drainage installation itself.

Connecting to a public sewer without authorisation is an offence under the Water Industry Act 1991, so the connection regime cannot be skipped even where planning and building control are both satisfied. Where the site is off-mains, a different regime again applies through the General Binding Rules for small sewage discharges. Keeping the three consents distinct, and confirming the discharge point before it becomes critical, is most of what stops drainage from holding up a start on site.

Frequently asked questions