Section 104 & 102 Agreement

 

A Section 104 Agreement is the usual route for new sewers to be adopted. Under section 104 of the Water Industry Act 1991, a sewerage undertaker – normally the relevant water company – can agree that sewers, drains communicating with its public sewers or sewage-disposal works will vest in it if they are constructed in accordance with the agreement. Once vested, they become part of the public system and the undertaker takes on maintenance.

Section 102 reaches existing sewers by a different route. It allows an owner to offer an existing private sewer or disposal works for adoption. Where sewers have already been built or brought into use without a completed Section 104 agreement, Section 102 is often the route to explore, but adoption is not automatic and the precise position should be checked with the sewerage undertaker.

 

 

What Section 104 actually says

 

The section is narrower and more precise than most summaries suggest. A sewerage undertaker may agree with a person constructing or proposing to construct a sewer, a drain intended to communicate with one of that undertaker’s public sewers, or sewage disposal works — that if the thing is built in accordance with the agreement, the undertaker will declare it vested in itself on completion, at a specified date or on some future event.

Three things follow. The agreement comes before construction, because it sets the standard the construction must meet. You can apply for one — section 104(2) gives a person constructing or proposing to construct a sewer the right to ask the undertaker to make an agreement. And what you end up with is a vesting declaration: ownership moves, and with it the maintenance liability, permanently.

A Section 104 is an agreement rather than an automatic consent, but the sewerage undertaker does not have the final word. If a person entitled to request an agreement and the undertaker cannot agree within a reasonable time, either can apply to Ofwat under section 105ZA of the Water Industry Act 1991. Ofwat can make an order that takes effect as a Section 104 agreement, subject to the statutory tests.

 

The standards — the DCG, not “sewers for adoption”

 

This is where a great deal of what you will read online is out of date, including some water company pages and a good many developer guides.

“Sewers for Adoption” is no longer the current adoption standard. Since 1 April 2020, the Codes for Adoption and Water UK’s Sewerage Sector Guidance have applied, with the Design and Construction Guidance in Appendix C. Older reports and specifications may still use the former name, so check which standard the design was actually prepared against.

The Design and Construction Guidance is a living document. Changes pass through the sewerage-adoption process and Ofwat can approve amendments. Use the current Appendix C on Water UK’s approved-documents page rather than relying on a version number or date copied into an older report or webpage.

One change from that shift matters more than the rest: the DCG broadened what counts as a sewer to include certain sustainable drainage components. Water companies in England can now adopt SuDS features described in the DCG under section 104, in the same way as pipes and manholes. If your last scheme predates 2020, that is the assumption most worth revisiting.

 

What it costs

 

There is no national fee and no national bond rate. Each water company sets its own, and they differ substantially — so we do not print figures here, and you should be wary of anyone who does.

What is consistent is the shape:

• An application or design check fee, charged by the water company. Some price it as a percentage of estimated construction cost; others charge flat fees that vary by the level of service and by whether the system is gravity or pumped
• A bond or surety, held for the duration of the agreement and callable if you fail to deliver to standard. Commonly calculated as a percentage of estimated construction cost — but at least one company applies a minimum figure regardless of percentage, so a small scheme is not necessarily cheap
• The works, built to DCG standard
• Maintenance during the rectification period, which is yours, not theirs

Ask your water company directly and get it in writing. Their published rates are the only figures that are true for your scheme, and they are revised.

None of this touches your planning application fee, which is a separate regime entirely.

 

The process, start to final certificate

 

The sequence is long and largely fixed:

• pre-design discussion with the water company — worth doing, and free at some companies
• application, with the design and supporting information
• technical review against the DCG and the company’s local practices
• the agreement is signed, and the bond put in place, before construction begins
• construction, with inspection
• as-built drawings provided
• provisional certificate of completion, once the company is satisfied
• a rectification period during which maintenance and repair remain yours
• final inspection, any remedial works, final certificate, bond released
• the vesting declaration — the sewers become public

The rectification period is set by the agreement rather than by statute, and it varies by company. Do not plan around a number you read somewhere; read your agreement.

If you need to start on site before the agreement is signed, some companies operate a formal early-start request. It is not a shortcut — if you have already laid and backfilled sewers, you may be asked to excavate and expose them so they can be inspected. That is an expensive way to save time.

 

Section 102 — when the sewers are already in

 

Section 102 lets the owner of an existing private sewer or sewage-disposal works ask the sewerage undertaker to adopt it. On a new development it is often considered where the proposed Section 104 route was not completed before the sewers were built or brought into use. That does not guarantee adoption, and the undertaker will assess the system that actually exists.

The differences from Section 104 are worth understanding before you rely on it:

• You must prove ownership. Only the legal owner of the sewer can offer it for adoption
• The company assesses what is actually there, not a design on paper. Expect a survey
• It is discretionary, and the criteria are about the network, not about you — whether the sewer is of suitable construction, whether it forms part of the general sewerage system for the area, whether it is accessible
• Some companies require the sewer to have been operating for a minimum period before they will consider it

Two recurring obstacles are difficult to cure after construction: the sewer was not built to an acceptable standard, or it is in a location that cannot be safely accessed and maintained. Neither problem is solved by paperwork alone. A sewer beneath a building or another permanent obstruction will normally create a serious adoption difficulty, and the undertaker will need to assess the actual layout and risks.

This is the argument for getting the Section 104 right at the outset. Section 102 exists, but it is a rescue, and rescues are not guaranteed.

 

Section 106 of the Water Industry Act is not a planning Section 106

 

Worth stating plainly, because both live on this website and they have nothing to do with each other.

Section 106 of the Water Industry Act 1991 is the right to connect a drain or sewer to the public sewer. It is a sewer connection application, made to your water company.

Section 106 of the Town and Country Planning Act 1990 is a planning obligation — affordable housing, contributions, biodiversity net gain. It is made with your council.

Different Acts, different bodies, different worlds. If someone tells you that you need “a section 106”, establish which one they mean before you do anything about it. On a housing scheme you may well need both, and they will be negotiated by different people on different timescales.

 

Sewers, highways and the rest of the picture

 

Sewer adoption and highway adoption frequently overlap. If a scheme includes a new estate road, a Section 38 Agreement may be progressing alongside the Section 104, and the drainage design may serve both the highway and the development. The technical approvals therefore need to be coordinated rather than treated as separate drawings produced at the last minute.

Where the works require apparatus to be placed or maintained in a public highway, identify the correct Section 50 licence or other highway permission and establish who will hold it. An accredited contractor can carry out the work, but that does not automatically transfer the licence holder’s statutory responsibilities.

As at 25 August 2026, Schedule 3 of the Flood and Water Management Act 2010 has not been commenced for England. The current English approach uses the planning system and national sustainable-drainage standards. Future statutory implementation should be checked again when a live project reaches design or application stage.

Section 104 & 102 relevant legislation

 

Read the “Changes to Legislation” panel at the top of each page before relying on the text. The technical standards are not in the Act — they sit in Water UK’s Sewerage Sector Guidance, which is revised independently.

• Section 104, Water Industry Act 1991 — agreements to adopt at a future date
• Section 102, Water Industry Act 1991 — adoption of existing sewers and disposal works
• Section 106, Water Industry Act 1991 — the right to connect to a public sewer, not a planning obligation
• Part IV Chapter II, Water Industry Act 1991 — provision of sewerage services

Developer contributions & planning agreements

 

Section 104 & 102 Agreement Page Updated: 25th August 2026