How Much Does a New Sewer Connection Cost?

The Water Company Fee: Section 106

Section 106 of the Water Industry Act 1991 gives you the right to connect to the public sewer, but you have to give your water company notice first and pay their application fee. A direct connection (where your drain joins straight onto the public sewer) usually costs more than an indirect one (connecting into a private drain that already runs to the sewer): Thames Water currently charges £330 for direct and £110 for indirect, and Anglian Water charges £327 and £116 respectively. Yorkshire Water charges £370 per private connection, or £939 where the new pipe is also being built to an adoptable standard and offered to the water company as a public lateral drain. Every undertaker publishes its own Scheme of Charges, revised each 1 April, so check your own water company’s current figure rather than relying on a national average.

Worked Example: A Short Garden Connection (8m, No Road Crossing)

Take a new foul connection running 8 metres from the house to an existing sewer at the boundary, entirely across lawn, with a direct Section 106 application to Thames Water:

• S106 application fee (direct connection): £330
• Excavation, pipe-laying and basic reinstatement at £40–£90 per metre, quoted by Mainline Groundworks as an inclusive rate: 8 × £40 to 8 × £90 = £320–£720
• Subtotal before VAT, pipe materials and any inspection chamber: ≈£650–£1,050

That subtotal covers the fee, the dig and basic reinstatement only. It does not include the pipe, bedding, backfill and inspection chambers a full job needs, which is what our sewer connection calculator works out from your pipe length, bends and junctions. For the fee side including VAT, bonds and inspection charges, use the drainage connection fee calculator. Once materials, a contractor’s labour margin and any inspection chamber are added, a simple garden connection like this commonly lands in the £1,500–£6,500 range that trade guides such as HomeBuyerCheck quote for groundworks plus the water company fee.

Why Crossing a Road Multiplies the Price

Once the pipe run has to cross a public road or footway, costs jump for three reasons. First, the excavation itself needs a permit from the highway authority: fees vary by council, for example Westmorland and Furness Council charges £401 for a street works permit (from 1 April 2026), plus £120 per non-compliant reinstatement inspection if the work fails. Second, the work must be carried out or supervised by contractors holding New Roads and Street Works Act 1991 (NRSWA) accreditation: the Act requires utilities to use trained and accredited staff and to secure the correct permits before any excavation on the public highway. Third, the surface itself must be reinstated to the Specification for the Reinstatement of Openings in Highways, a much stricter, layered standard than turf or a domestic patio.

Those three factors compound quickly. BookABuilderUK’s 2026 cost guide gives an example of 25 metres including a road crossing at about £3,500 in labour alone, against roughly £1,200 for 15 metres of soft garden ground. JW Clark’s own worked examples for a full highway sewer connection, including permits, traffic management and reinstatement, run from around £7,000–£9,000 at 1 metre depth up to £25,000–£35,000 at 6 metres, since deeper trenches need more excavation, more support and longer road closures. If there is any way to route the connection through a garden or driveway instead of under the carriageway, it is worth asking your contractor to price that option first.

Build-Over Agreements

If your build works within 3 metres of a public sewer, or directly over it, you need the water company’s consent before you start, known as a build-over (or build-near) agreement. This is separate from the S106 connection fee and applies even if you are not connecting a new drain: it is about protecting the existing sewer during construction. Thames Water bands its charge by sewer diameter: £130 for Class 1 (up to 175mm, the most common size for a domestic lateral), £490 for Class 2 (176–350mm) and £585 for Class 3 (over 350mm), with additional legal costs starting at £1,000 for the largest sewers. A CCTV survey before and after construction is normally required so the water company can confirm the sewer was not damaged. Fees and diameter bands vary by undertaker and are revised each 1 April, so confirm the current figure with your own water company.

What Moves the Price

• Distance to the sewer: every extra metre adds excavation, pipe and reinstatement cost, roughly £30–£90/m on soft ground
• Depth: deeper trenches need more excavation, more support and, on a highway crossing, longer closures, which is why JW Clark’s examples roughly triple in cost from 1m to 6m depth
• Road or footway crossing: triggers permits, NRSWA-accredited labour and highway-standard reinstatement, the biggest single jump in the table above
• Ground conditions and obstructions: rock, high water table or other services in the trench line add plant and labour time
• Pipe material and cover depth: rigid clay or concrete pipe needs deeper cover under a driveway or road than flexible plastic pipe; see our drainage pipe depth answer for the Approved Document H minimums
• Adoption status: building the new pipe to an adoptable standard, so the water company takes it on as a public lateral drain, carries a higher application fee (Yorkshire Water’s £939 versus £370)
• Region: BookABuilderUK’s 2026 guide puts London and South East groundworks costs 15–30% above the rest of the UK, driven by labour rates and permitting

Before You Start

Most existing homes are already connected to the mains sewer. A drainage and water search (CON29DW, typically £40–£75) confirms this before you assume you need a new connection at all, so this cost mainly applies to new builds, conversions, extensions that add a new drain run, and properties currently on a septic tank or cesspit. Ask your water company for a sewer map of the area first: it shows the pipe size, depth and whether the connection you are planning is direct or would need to cross a road. Get at least three quotes from contractors experienced in sewer connections, and check whether VAT applies: connection works carried out in the course of building a new dwelling are zero-rated, while a connection to an existing property is normally standard-rated at 20%, covered in more detail on the drainage connection fee calculator above.

Fee figures verified against Thames Water and Yorkshire Water’s published Scheme of Charges and build-over agreement pages, and Anglian Water’s 2026 charging arrangements, all checked July 2026 (undertakers revise charges every 1 April, so confirm the current figure with your own water company). Groundwork and reinstatement ranges cross-checked against Mainline Groundworks, GardenCost and BookABuilderUK 2026 cost guides; highway-crossing project totals from JW Clark’s published worked examples; road opening permit and NRSWA accreditation figures from Westmorland and Furness Council and Depotnet, checked July 2026 (permit fees are set individually by each highway authority and vary by council). These are indicative UK estimates, not quotes. Last updated: July 2026.