Whatever happened to Sewers for Adoption?

Sewers for Adoption was the design guide that told developers how to build a sewer a water company would take over. It stopped doing that job in England on 1 April 2020, when Ofwat's Code for Adoption Agreements came into force and brought the Sewerage Sector Guidance with it. The technical standard now sits in Appendix C of that guidance, the Design and Construction Guidance, currently version 2.3 and dated 11 November 2023.

The 8th edition most people go looking for was written, consulted on, and then overtaken by the framework that replaced it. It never took effect in England. Wales went its own way and still works to the 7th edition with a 2019 addendum.

Around 150 people a month in the UK still search for a document that has not governed sewer adoption in England since April 2020, and that number has been climbing rather than falling.

What replaced Sewers for Adoption?

Three documents replaced it. They do different jobs, and conflating them is the source of most of the confusion. Ofwat's Code for Adoption Agreements sets the rules water and sewerage companies must follow when they adopt. The Sewerage Sector Guidance sits beneath the Code and carries the detail. Appendix C of that guidance, the Design and Construction Guidance, is the technical standard the pipes themselves have to meet. Together they took over from Sewers for Adoption 7th edition across England on 1 April 2020.

The split matters more than it looks. Under Sewers for Adoption one book held both the process and the engineering, and every water company applied it with its own house amendments, which is why the same design could be accepted in one region and sent back in another. The Code separated the two, standardised the procedural requirements across England, and isolated the engineering in a single appendix that an industry panel can amend without renegotiating the wider framework. So the guidance carries a version number and a change log. The version you designed to two years ago may not be the one being checked today. Water UK publishes the current approved documents in one place.

None of this touched the legal machinery. Adoption still runs on a Section 104 agreement under the Water Industry Act 1991, and the right to connect still sits in section 106 of the same Act, unaffected by any of this. What changed is the specification the drawings are measured against. A foul drainage strategy for your development that confirms a mains connection should also be clear about whether the pipes behind it are being built for adoption, because the two answers have different consequences for whoever ends up maintaining them.

What happened to the 8th edition?

The 8th edition exists. Water UK and WRc drafted it in 2018 and put it out for consultation, and the draft is still on Water UK's website, which is why it keeps turning up in search results. What it never did was take effect as the standard for England. While it was being finished, Ofwat decided that adoption should run to a single mandatory national framework rather than an industry design guide, and the Code absorbed the work. The 8th edition ended up as the last draft of a document that was replaced instead of published.

The name survives in a few corners. Some new appointments and variations, the smaller companies that take on sewerage for a single development, still publish their own addenda to the 8th edition, so a developer working with a NAV rather than the regional water company can be handed a document that a developer two miles away would not recognise. Where the incumbent undertaker is adopting in England, the position is simple. The Design and Construction Guidance is the standard, and it says so itself.

Local Practices are the escape valve, and they are easy to miss. Individual companies publish approved departures on their own websites, covering easement widths, pumping station details and similar, and those sit alongside the national text rather than replacing it. Check both before a design goes in.

What the Design and Construction Guidance actually covers

The guidance runs to 214 pages in six parts and seven appendices, and it is far more specific than most people expect. It is not a policy document. It gives pipe sizes, gradients, clearances, testing regimes, materials standards, the permissible deflection at a pipe joint, and the colour of the wiring inside a pumping station kiosk.

• Part A, general. Scope, definitions, the drainage strategy, statutory consents, and what to do about existing public sewers and lateral drains already crossing the site.
• Part B, foul sewers and lateral drains. Hydraulic design, layout and access, the five manhole and inspection chamber types, structural design and testing.
• Part C, surface water systems. What can be adopted at all, hydraulic design, and a clause for each SuDS component from swales to soakaways.
• Part D, pumping stations. When one is justified, how far it must sit from housing, how much storage it needs and how the rising main is designed.
• Part E, civil engineering specification. Materials, excavation and backfilling, concrete, construction of pipes and chambers, cleansing and testing.
• Part F, mechanical and electrical specification. Pumps, motors, control panels, valves and telemetry for stations up to 30 kW per pump.

Two appendices earn their keep on a live project. Appendix I lists what the CDM health and safety file has to contain when the sewers change hands, down to the manufacturer's delivery note proving which geocellular product actually went into the ground. Appendix VII standardises the drawing symbols and their colours. A foul sewer is brown and a surface water sewer dark blue on every adoption drawing in England.

The guidance is a specification, not advice: compliance is mandatory except where a sewerage company has published an approved Local Practice.

What it asks of a scheme

Most of the guidance is unremarkable, conventional good practice. A handful of numbers do the damage. They differ between foul and surface water systems, in ways that catch out anyone treating surface water as a variation on foul, and they are stricter than the equivalents in Building Regulations Part H that a designer may be more used to working with.

Layout is where adoptability is usually won or lost, and it is settled long before a drainage engineer is appointed. Sewers belong in highways or public open space, not enclosed private land. The outside face of a sewer has to be at least 1.2 metres from any building or structure, or as far from it as the sewer is deep below the foundation, whichever is the greater. Inspection chambers can be no more than 45 metres apart, manholes no more than 90. Nothing may be planted closer to a sewer than the width of its own canopy at mature height. A layout fixed without those in mind can be perfectly good engineering and still unadoptable. Our free drainage calculators cover the gradients and chamber sizing, and BS EN 752 sits behind much of the layout thinking, as BS EN 12056 does inside the building.

Surface water pipes are designed not to surcharge in a one-year storm on a sloping site, while the lead local flood authority is asking the same scheme to manage a one-in-100-year event plus climate change. Both are correct. They measure different things, and the gap between them is where sewer flooding starts.

Why the guidance still will not adopt most of your SuDS

This is the part that surprises people. It is a definition problem, not a design problem. To be adopted as a sewer a drainage component has to satisfy four tests in the guidance at once, and a great deal of perfectly good sustainable drainage fails one of them.

• It drains buildings. The component is constructed for the drainage of buildings, and of yards belonging to buildings.
• It has a channel. A depression between banks or ridges, with a definite boundary.
• It conveys and returns flow. To a sewer, to a surface water body, or to groundwater.
• It has an effective discharge point. With a lawful right to discharge, secured by the developer and transferred to the sewerage company on adoption.

The exclusions follow from the tests. A green roof, a pervious driveway and a rainwater pipe are part of the structure of a building. A pervious street and a kerb channel are part of the structure of a street. Filter strips have no channel. None of them can be a sewer, so none can be adopted by a water company, however well they are designed. A soakaway has no channel either. It is adoptable only if the pipe feeding it is itself a sewer being offered for adoption, which is a common way for a plot-level infiltration scheme to arrive at the technical check with nothing in it the undertaker is able to adopt.

Swales, rills off the street, bioretention, ponds, wetlands, basins, attenuation tanks, infiltration trenches and filter drains can all be adopted, and surface features sized for a one-in-100-year event plus climate change normally will be. What the guidance asks in return is evidence, and a good deal of it: a completed set of design assessment checklists drawn from the CIRIA SuDS Manual, a management and maintenance plan setting out the activities, their frequency, their duration and their estimated cost, and a five-year establishment plan for anything planted. Much of it maps onto the national SuDS strategy templates a planning authority will separately expect.

Of around 170 SuDS adoption applications made to the six largest water companies over three years, only about three succeeded, according to Home Builders Federation research published in October 2025.

Whatever a water company will not take on has to be maintained by somebody else, and that somebody is usually a management company funded by an estate charge on the people who buy the houses. Designing to the four tests early is the difference between a maintenance plan and a surprise. Resolve it in a surface water drainage strategy built to an adoptable standard, not at the technical check. It is also where the 2025 National Standards for SuDS (published by Defra), the discharge hierarchy and any biodiversity net gain claim have to be reconciled with what will actually be adopted.

Wales did not follow England

The Design and Construction Guidance applies only to sewerage companies operating wholly or mainly in England. Dŵr Cymru Welsh Water is the one company that sits mainly in Wales with part of its area in England, and it still works to Sewers for Adoption 7th edition with an addendum issued in March 2019.

Wales also did something England has not. It commenced Schedule 3 of the Flood and Water Management Act 2010 in January 2019, creating statutory SuDS Approving Bodies and making surface water drainage subject to their approval before anything is built. England has not followed. Schedule 3 remains uncommenced here, and the House of Commons Library recorded in 2026 that the government would rather improve planning policy, adoption and maintenance than bring it into force, with a decision to come "in due course".

The practical result is that the same scheme, designed either side of the border, is measured against a different standard by a different body.

The guidance itself notes that this will change when the Wales Act 2017 provisions commence. Until they do, a developer working on both sides of the border is working to two rulebooks.

Which version applies to your scheme today

When someone asks for the latest edition of Sewers for Adoption, this is the document they are actually looking for. Version 2.3, dated 11 November 2023, is the current Design and Construction Guidance, and has been for nearly three years. The wider Sewerage Sector Guidance above it moved to version 2b in February 2025, and its terms of reference to a September 2025 revision. Any page still calling version 2.2 current is out of date. That happens more often than it should.

1. Version 1.0, 25 October 2019. Approved by Ofwat, ahead of the Code taking effect the following April.
2. Version 2.0, 10 March 2020. A change to clause E2.21.1, on thermoplastic pipes for gravity sewers.
3. Version 2.1, 25 May 2021. Changes to five figures and to the layout clause at B5.2.4(a).
4. Version 2.2, 29 June 2022. A change to clause C7.8.4(d), on attenuation tanks.
5. Version 2.3, 11 November 2023. A change to clause C7.1.2, on infiltration components.

The changes have been narrow rather than wholesale, which is the point of the structure. Version 2.2 rewrote the clause on attenuation tanks, adding a requirement that half-pipe and arch structures show how they can be cleaned and jetted without eroding the base material or the membrane. Version 2.3 rewrote the clause on infiltration components. Neither is the sort of change a designer notices unless they are looking for it. Both will fail a technical check.

The guidance is still moving

Five change proposals are open with the Water UK Sewerage Adoption Panel as this is written, the most recent lodged on 9 September 2026. Anyone can submit one. The Panel considers it and Ofwat makes the final decision, which is how a national standard gets amended without anyone having to print a new edition.

• Yorkshire Water, 9 September 2026. Manual handling requirements for manholes.
• ViaCon, 20 July 2026. New clauses covering polymer-coated corrugated steel attenuation systems.
• Panel terms of reference, 20 May 2026. An amended draft submitted to Ofwat for review.
• TT Pumps, 20 February 2026. Pumping station flow rate calculations, and septicity.
• ViaCon, 18 September 2025. Approval of corrugated steel pipe tanks for below-ground attenuation and storage.

Two closed recently. Torrent Water Management's addition of HDPE for manhole raising sections at clause E6.7 got an Ofwat decision in February 2025, and John Davidson Pipes' proposal on consistency between two pipe clauses was decided in March 2024. Both are small. Both change what a technical checker will accept. The open proposals are published as they are lodged.

A national standard that can be amended clause by clause is easier to keep current than a printed edition, and much easier to fall behind.

Sewers for Adoption is not coming back, and the standard that replaced it moves in small steps rather than editions. If you are designing drainage you want a water company to adopt, check the version number at the start of the project rather than at submission. Unda prepares drainage strategies for planning written to the standard actually in force, covering both foul drainage and surface water, and says at design stage which parts of a scheme will be adopted and which will not. We also handle the discharge of drainage planning conditions once permission is granted.

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