Water and sewerage connection charges explained

The sewer connection charge on a new build is rarely a single number, and self-builders who budget for one usually find three. There is the infrastructure charge the undertaker levies for each new connection, the cost of the physical connection itself, and, where the mains do not reach the site, the cost of requisitioning a new sewer or water main. All three sit under the Water Industry Act 1991, all three are charged by the water and sewerage undertaker rather than by the council, and none of them is covered by your planning fee or your Community Infrastructure Levy liability.

The right to connect and what limits it

Section 106 of the Water Industry Act 1991 gives the owner or occupier of premises the right to have drains and private sewers communicate with the public sewer. The right is not absolute. The undertaker can refuse by notice within 21 days of the connection notice, on the grounds set out in the section, which include that the mode of construction or condition of the drain is unsatisfactory or that connection would be prejudicial to the sewerage system.

Two practical points follow. Surface water is where refusals concentrate, because an undertaker facing a combined or overloaded system will resist taking more of it, and national policy expects surface water to be dealt with on site wherever it can be. If your scheme assumes a surface water connection to a public sewer, get that confirmed before the layout is fixed rather than after.

The second point is that a refusal can be appealed, and the fact that the route exists is often enough to reopen a conversation. Take advice on the current appeal route before relying on it.

Infrastructure charges and what they fund

An infrastructure charge is levied for each new connection to the water supply network and each new connection to the sewerage network. It is a contribution towards reinforcing the wider network rather than a payment for the pipe outside your plot.

Two features catch people out. The charges are set annually in each undertaker's charges scheme and vary between companies, so a figure quoted by a friend who built in another region tells you nothing about yours. And the charge is normally levied per new property, which means a plot split creating two dwellings attracts two sets, while a replacement dwelling on the footprint of a demolished one may attract a credit or none at all, depending on the scheme.

Check the current charges scheme published by your undertaker for the year in which the connection will be made, not the year you are budgeting in, because the figures are reviewed annually.

Requisitioning a main or a sewer

Where there is no public sewer or water main within reach, you can require the undertaker to provide one. Section 98 covers the requisition of a public sewer for domestic purposes and section 41 the requisition of a water main. The undertaker must comply, subject to conditions including the payment of a deposit and an undertaking to meet the relevant deficit.

The financial mechanism is the part worth understanding. The cost of the new main or sewer is set against the income the undertaker expects to receive from the properties it will serve over a defined period. Where the expected income covers the cost, the requisitioner pays little. Where the scheme is small and the run is long, the shortfall falls on the requisitioner, and on a single house at the end of a field it can be the largest single infrastructure cost in the project.

Programme matters as much as price. A requisition involves design, land access, wayleaves or easements across third party land, and construction. Start it at the point you have a planning decision, not at the point you want to move in.

Diversions and build-over agreements

If a public sewer crosses the plot, two questions arise. Building over or close to it requires the undertaker's agreement, and the standard build-over agreement will set conditions on foundation type, distances and access to manholes. Some undertakers deal with this under a self-certification route for simple cases and require a full agreement for the rest.

Diverting the sewer is the alternative, and it is expensive. Section 185 allows an owner or occupier to require the undertaker to alter or divert a pipe, at the requisitioner's cost, subject to the undertaker being satisfied it is reasonably practicable. Get the sewer records early. A plot that looks straightforward can be halved in value by a rising main running diagonally under the proposed footprint.

Timescales to build into the programme

Each process has its own clock and they do not run in parallel by default. A pre-development enquiry, which tells you what capacity exists and what the undertaker will require, takes a matter of weeks. A build-over agreement is usually quicker than a requisition and slower than a connection. A requisition involving easements across land you do not own is the one that runs to months, because it depends on a third party signing something.

The sequence that works is to raise the pre-development enquiry during the planning application rather than after the decision. By the time permission is granted you then know whether the drainage strategy you submitted is deliverable, which is the point at which changing it still costs little. The Drainage Strategy submitted with the application should reflect what the undertaker has actually said, and a Foul Sewage Assessment is often the document the council uses to check that it does.

Where the figures move

Infrastructure charges are reviewed annually in each undertaker's charges scheme. Requisition calculations move with construction costs and with the income offset assumptions. None of these are figures to fix in a budget 18 months ahead and forget.

Build a contingency around the requisition specifically, because it is the item with the widest range. A connection to a main in the road outside is a known cost. A requisition across 200 metres of a neighbour's field is not, until the easement is agreed.

What to do at the pre-development stage

1. Order sewer and water records for the site and the surrounding streets before you commit to a layout.
2. Raise a pre-development enquiry with the undertaker covering both water supply and foul and surface water drainage.
3. Establish whether any surface water connection is available, and design for on-site management on the assumption that it is not.
4. Identify any public sewer crossing the plot and decide early between building over and diverting.
5. Price the infrastructure charges from the current charges scheme, separately from the connection cost.
6. Put the requisition, if one is needed, on the critical path in the programme.

These charges sit alongside the planning costs rather than inside them, and the same is true of the levy. Our notes on calculating your CIL liability from the charging schedule and on section 278 highway works cover the two other cash calls that arrive in the same period. For the application documents themselves, PlanScope pricing sets out the free report, the £50 per report option and the Professional tier.

This is general guidance, not legal advice, and you should check the position with your water and sewerage undertaker and your local planning authority before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.