Section 104 – Public Sewer Connection – Thames Water Area

What is a Section 104 Adoption Agreement:

When a new development is planned, the Developer has the opportunity to construct the sewers using approved materials and to a standard which makes them suitable for adoption by the sewer provider when construction is complete. An adoption agreement can be entered into under Section 104 of the Water Industry Act 1991 prior to the sewers being built. This is the most desirable arrangement and if all new developments were covered by such adoption agreements, there would be few, if any, new private sewers on housing estates. However, there are many kilometres of existing private sewers that were built without an adoption agreement in place. Section 102 of the Water Industry Act 1991 provides for the adoption of such sewers to be considered.

It is important to draw a distinction between sewers, drains, lateral drains, and developments

Development Example 1: Fronting Existing Highway

Separate developments connected to the public sewer each with own adopted lateral drain

Development Example 2: Drains Not Adopted within Development boundary

Adopted lateral drain connecting development to sewer

Development Example 3: Drains Adopted within development boundary

Adopted lateral drain connecting last house. Adopted Sewer for connecting all other house

Thames Water (Section 104 adoption agreement)

Unfortunately TW do not differentiate between development examples.

The adoption process and fees for example 3 are applied to examples 1 & 2.

Drawnings: (example page 3)

Drawings to comply Thames Water local practice and in conjunction with the Design and Construction Guidance for foul and surface water sewers offered for adoption under the Code for adoption agreements for water and sewerage companies operating wholly or mainly in England (“the Code”)

Fees: (example page 4)

Same fees for 1 or 100 properties (only change in fees is the value of construction costs).

Time Scale: (process example page 5)

Approval acceptance period between 6 to 8 month.

Example drawing for section 50 licence pre May 2023

Example drawing for section 50 licence post May 2023

Thames Water Fees & Indicavative On-Costs

Thames Water S104 Adoption Proccess

Do you need assistance?


Find the answers to some of the most commonly asked questions.

Learn more

Find us

P4 Allen House Business Centre The Maltings, Station Road Sawbridgeworth Herts CM21 9JX

Google maps

Contact us

Discuss your project with a member of our head office team today.

Learn more

Contact us

Premier Drainage Solutions
P4 Allen House Business Centre
The Maltings, Station Road
Herts CM21 9JX

Request a call

Our charity

MSA Trust receives no government support and relies entirely on charitable donations to fund their support services as well as research into finding the cause and cure for multiple system atrophy (MSA).