If you’re planning on connecting your drainage system to the main public sewer system, you may have discovered that new sewer connection costs can be complicated; a lot depends on the specifics of the site. It’s because of this that the team here at Premier Drainage often hesitates when we’re asked to give a ballpark figure for work, even if it’s ‘just as a guide’.
We believe that when it comes to mains drainage connection costs, it’s far better to have a detailed quotation, rather than use some kind of ready reckoner – and it doesn’t have to cost you anything to get this important information.
We always advise it’s far better to get a proper quote from the off, because this means you have dependable drainage cost figures to work with. This is why we offer a no-obligation free quotation service, because we firmly believe that you shouldn’t have to spend money in order to plan your build budget properly.
In this article, we’ll break down what affects sewer connection costs and explain some of the fixed costs to expect when applying for sewer connection permission.
What affects the cost of connecting to public sewers?
So, why is it complicated to estimate mains drainage connection costs? Well, there are a lot of variables involved when calculating the cost, because every site and development is different.
Boiled down to the absolute basics, the factors involved in calculating the cost of a new sewer connection include:
- Pipework – The length, depth and diameter of the public sewer
- Logistics – Getting the actual work done
Let’s look at these in a little more detail.
Pipework: The length of the pipework is dictated by the location of the nearest mains sewer. The diameter is determined by the size of the development and the volume of waste that the sewerage pipes will need to accommodate. The depth of the pipework will depend on how the required falls will be achieved – much of our sewer system relies on gravity, so depending on the distance and terrain level, deeper trenches may need to be built.
Logistics: The logistics of connecting to the main sewer include any aspect which impacts the process. This could be restrictions on machinery use owing to tight site dimensions in urban areas, the need to implement traffic control measures, any onsite drainage that’s required during the build, and any other elements unique to the site in question.
There may be a variety of other factors that could possibly affect the cost of connecting to a main sewer, such as which water company you’re working with. You’ll find there are differences in their procedures and charging structures, which can impact your eventual bill, including whether you need to build the boundary manhole.
How much do sewer connection applications cost?
Much more predictable are the costs associated with making the necessary applications to the water company: Section 106 (consent to connect) and Section 104 (sewer adoption). Read our helpful guides to learn everything you need to know about these applications, from why you might need them, how to apply, and how they work.
These application costs vary depending on your local water company. We work across the east and southeast of the country, in areas served by Thames Water, Anglian Water, and Southern Water, each calculating its charges in different ways.
To lend you a hand, we’ve prepared a list of fixed application costs for each water company we work with to consider when planning your budget. Please note that these prices are correct as of June 2026 – for completely up-to-date costs, it’s best to visit the water company websites directly, or get in touch with us for help. This is also advised for other unique fluctuating costs not written below.
Thames Water currently charges:
S104
- S104 application cost: £1,725
- Project management and inspection fee: 1.4% of the estimated construction cost
- Legal fee (adoption agreement): £1,050
- Easement fee (to formalise access rights): £905
- Security deposit: either £5,000 or 10% of the construction cost estimate
S106
- S106 application cost for a direct connection: £360
- S106 application cost for an indirect connection: £290
Anglian Water currently charges:
S104
- Foul sewer only:
- First 100 plots or fewer: £814
- Per 100 plots thereafter (or part thereof): +£366
- Surface water only:
- First 100 plots or fewer: £936
- Per 100 plots thereafter (or part thereof): +£427
- Additional S104 add-on applications
- Pumping station (per item): £488
- SuDS (per application): +£651
- If you plan to build both a foul sewer and surface water sewer, they must be applied for separately, and the application costs will be stacked.
Other charges:
- Supervision (site inspection): 2% of estimated construction cost (minimum charge £1,058)
- Surety: 10% of estimated construction cost (minimum charge £5,000)
- Legal agreement: £628 (complex amendments charged at £151 per hour)
- Fourth and further vetting task fees will apply (three vetting tasks are included in the standard fee)
S106
- S106 application cost for a direct connection: £549
- S106 application cost for an indirect connection: £285
- S106 application cost for public lateral drain adoptions: £407
Southern Water currently charges:
S104
- S104 application cost: £668
- Inspection fee: 2.5% of the construction value
- Legal fee: £518
- Bond: 10% of the construction value
S106
- S106 connection to existing sewer/manhole application cost: £299
- S106 manhole construction application cost: £369
To assist further, here are some real-life examples of new sewer connection costs for projects we have completed recently, to give you a benchmark for how much sewer connections typically cost:
Sewer connection & new pumping station
Asset owner: Thames water
Locations: East Molesey, Surrey county Council
Depth:1.5m
Existing sewer: 225mm
New lateral length: 7.5m
Connection method: New manhole over main
Project value: £29,800
Sewer connection (timber heading)
Asset owner: Thames water
Locations: London Borough of Camden
Depth:4m
Existing sewer: 1397 x 864 Victorian sewer
New lateral length: 12m
Connection method: Preformed saddle
Project value: £59,600
On site foul & surface water diversions
Asset owner: Anglian water
Locations: Brentwood, Essex
Depth: 2m
Existing sewer: 150mm & 225mm
New lateral connection: F/W 30m S/W 45m
Connection method: Existing manholes
Project value: £44,400
Sewer connection
Asset owner: Thames water
Locations: London borough of Wandsworth
Depth: 1.5m
Existing sewer: 150mm
New lateral length 17m
Connection method: Preformed junction
Project value: £30,600
Misconnection
Asset owner: Anglian Water
Locations: Little Claton, Essex
Depth: 3.5m
Existing sewer: 150mm
New lateral connection: 8.5m
Connection method: Existing Manhole
Project value: £17,700
Sewer connection
Asset owner: Thames water
Locations: London Borough of Lambeth
Depth: 3.5m
Existing sewer: 300mm
New lateral length: 7.5m
Connection method: Pre-formed junction
Project value: £25,600
Achieving the best value with new sewer connection costs
If you’ve looked at the links above to each water company’s charging structure details, you’ll notice that all three companies – Thames Water, Anglian Water and Southern Water – also give ready-reckoner costs for doing the new sewer connection works.
Our view is that it’s much better to deal with a contractor directly and get a detailed quotation for the works required than it is to use a water company’s sub-contractor. Our past customers have found our quotes highly competitive in comparison to the charges indicated by water companies.
To get a free quotation for a new sewer connection on your project – which will enable you to plan your build costs with proper certainty – call us on 01268 950050 or send an email to [email protected].
