Getting a sewer connection agreement under the Water Industry Act

A sewer connection agreement is granted by the sewerage undertaker, not by the council, and the right behind it sits in section 106 of the Water Industry Act 1991. That section gives the owner or occupier of premises the right to connect a drain or private sewer to the public sewer, subject to notice and to the undertaker's power to refuse in defined circumstances. A planning permission that assumes a connection proves nothing about whether one is available.

Two clocks run in parallel on any site of scale. The planning clock is eight or thirteen weeks with extensions. The drainage clock covers a capacity check, a technical design approval, sometimes a requisition for a new sewer, and any off-site reinforcement the network needs. The second clock is longer and it is the one that decides your start on site.

The right to connect and its limits

Section 106 is a right, not a discretion, but it is a qualified one. The undertaker may refuse where the mode of construction or the condition of the drain or sewer is such that connection would be prejudicial to its sewerage system. Refusal has to come within 21 days of the notice, and a refusal carries a statutory appeal route.

Three practical limits sit underneath that.

The right applies to foul drainage. There is no equivalent right to discharge surface water to a public sewer, and undertakers routinely refuse surface water connections where an alternative exists, which is the position national policy expects them to take.

The connection point has to be a public sewer. Many sites are nearer a private drain, a lateral drain or a sewer whose status changed in the 2011 transfer of private sewers, and status has to be confirmed from the undertaker's records rather than assumed from a manhole cover.

And the right says nothing about capacity. A connection that the network cannot absorb is exactly the situation the undertaker will treat as prejudicial, which turns a right into a negotiation about phasing and off-site works.

Capacity assessments and pre-development enquiries

Every undertaker offers a pre-development enquiry, and it is the best value week you will spend on a major site. You provide the site boundary, the number of units or the floor area, the anticipated foul flows and the intended connection point. You get back a view on the receiving network, any known constraints and an indication of whether reinforcement is needed.

Ask for three things specifically. Where the nearest public foul sewer is and its status. Whether the receiving system, including any pumping station and the treatment works, has headroom for your flows. And whether the works has a discharge permit constraint that limits growth in the catchment.

That last one is the constraint developers miss. A treatment works operating close to its permitted limit can hold up an otherwise unremarkable scheme, and the fix is a capital programme item rather than a design change. Where nutrient neutrality applies in the catchment, the treatment works position and the planning position become the same conversation.

For a site with any complexity, put the undertaker's written response into the application. A Foul Sewage Assessment that quotes the enquiry reference, the flows assumed and the undertaker's own words is much harder to argue with than a paragraph asserting that connection is available.

How a connection application differs from planning approval

The council decides whether the development is acceptable in planning terms. The undertaker decides whether the pipework can be built and connected, and whether it will adopt what you build.

Adoption is the one that shapes the layout. A section 104 agreement is negotiated against the sewerage sector's design and construction standards, and those standards drive pipe sizes, gradients, manhole positions, easement widths and the distance between a sewer and a building. A layout drawn without them will be redrawn.

The build over agreement catches infill and extension schemes. Since the 2011 transfer, many pipes that owners believed were private drains are public sewers, and building over or within the protected distance of one needs the undertaker's agreement, sometimes with a diversion under section 185.

Timescales and where they collide with the planning programme

The statutory 21 day window for refusing a section 106 notice is the only fixed period in the sequence. Everything else takes as long as the design iterations take.

A pre-development enquiry is typically a matter of weeks. A section 104 technical approval depends on how close the first submission is to the standards. A section 98 requisition, where the undertaker has to build a new public sewer to serve your site, involves a formal requisition, a financial calculation, land or easement acquisition and a construction programme, and it is measured in many months rather than weeks.

Off-site reinforcement is longer still, because it competes for space in the undertaker's investment programme rather than yours. So the honest advice for a site that needs reinforcement is to start the conversation at option stage and to build the risk into the land price.

Requisitioned sewers and offsite reinforcement

Requisition under section 98 is the route where no public sewer is reasonably close and the undertaker is required to provide one for premises used for domestic purposes. The developer contributes, the undertaker builds and the asset is public from the outset.

The calculation matters. The developer's contribution reflects the cost of the works set against the income the undertaker will receive from the new properties over a defined period, so a scheme with many units in a short run of pipe can end up with a modest bill, while a handful of houses at the end of a long main can be expensive. Get an indicative figure before you commit.

Off-site reinforcement is different again. It is work in the wider network needed because your flows tip an existing constraint, and there is no equivalent statutory duty to deliver it to your programme. This is where a Grampian condition and a phasing plan do the work.

Grampian conditions requiring capacity before occupation

Where capacity will exist but does not yet, the standard planning answer is a negative condition preventing development or occupation until the necessary works are complete. The Grampian principle allows a condition requiring works on land outside the applicant's control, provided there is a reasonable prospect of the action being performed within the life of the permission.

Wording decides how painful it is. A condition tied to occupation of the first dwelling stops the whole site. A condition tied to occupation of a specified phase lets the earlier plots complete while the reinforcement is delivered. Undertakers will often confirm which trigger they need, and agreeing the wording before the decision is issued is far easier than a section 73 application afterwards.

Check the condition against the six tests in national guidance as well. A condition that duplicates a separate statutory control is not necessary, and undertakers sometimes ask for conditions that simply restate section 106.

Evidence to submit with the planning application

Keep the drainage evidence in one place and make it match the layout drawings.

1. The pre-development enquiry response, with its reference and date.
2. A foul drainage strategy showing the connection point, its status as public or private, and the route.
3. Calculated foul flows for the completed development, with the assumptions stated.
4. A statement on surface water, showing it is separated and dealt with elsewhere, cross-referenced to the Drainage Strategy.
5. Any build over, diversion or easement issues, with the undertaker's position.
6. A phasing plan where reinforcement is needed, with proposed condition wording.

Where wider utility capacity is also in question, an Utilities Assessment pulls water, power and telecoms into a single document so the officer is not reading five separate letters. And if the site is also constrained by flooding, the Flood Risk Assessment should cross-refer rather than repeat the foul position.

This is general guidance, not legal advice. Sewerage undertakers apply their own procedures and charges, so confirm the position in writing with the undertaker and your local planning authority before relying on it.

Get the drainage evidence drafted while the capacity enquiry is running. Browse the report types by category to see what a serviced site normally needs.

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