If you are building a new home, converting an outbuilding or putting an annexe in the garden, the water connection is one of the few jobs on the list that runs to someone else’s timetable. It involves the water company, your own builder or plumber, and a pipe that has to cross a boundary, and the ground between your plot and the water main decides most of what you pay.
Every water company publishes its own process and charges. To keep things concrete, this guide uses Affinity Water’s published process and its charges for 2026/27 as a worked example. The steps are broadly similar elsewhere, but always check your own company’s figures before you budget.
The water company comes first
A new connection starts with an application to the water company, not with a contractor. Whoever owns the property makes that first contact. Affinity says its online application takes around 20 minutes, asks how many properties you want to supply and whether they are domestic, and that it will accept the application or ask for more information within five days.
The water company then works out what the connection needs. Affinity’s cost advice arrives within 28 days and confirms the size, material and location of the new connection, together with survey drawings. It also flags anything likely to cause delay, such as a road closure. Usefully, it is issued as a “convertible quote”, meaning it shows the price of the water company doing the work alongside the cost of appointing an accredited self-lay provider instead.
The practical lesson is to apply as soon as planning permission is in place. Nothing on the water company’s side starts until your application arrives, and the cost advice shapes several decisions you will want to make before groundworks begin.
What the bill is made of
The charges fall into two groups. The first is a set of fixed charges per property. Under Affinity’s 2026/27 charging arrangements, these include an infrastructure charge of £615, an environmental component of £127 (which can be offset by an incentive where the home meets Affinity’s water efficiency criteria), an application fee of £185 and an administration fee of £125.
The second group is the connection itself, and this is where the ground matters. Affinity’s 2026/27 charge for a standard 25 to 32 mm single connection, which includes the meter, is:
- £2,334 where the connection is made in a road
- £2,097 in a footpath
- £1,957 in unmade ground
- £632 where the excavation is done by others
Laying the pipe is then charged per metre on the same basis, from £174 a metre in a road and £153 in a footpath to £112 in unmade ground and £64 where the excavation is done by others. Affinity’s own worked example for a single house connection in a road also adds £952 for traffic management. All of these figures are before VAT.
That “excavation by others” rate is worth understanding. Affinity explains that it applies where the trench has been dug by you to its standards, and that it only backfills and reinstates sites it has excavated itself. The lower figure is not a discount. It reflects that someone else is doing the digging and the reinstatement.
Put simply, the surface between your boundary and the main, and the distance to it, drive most of the bill. A connection made across a verge costs far less than one that has to cut into a road with traffic management in place.
Where your responsibility starts
There are two pipes involved, and they belong to different people. Ofwat explains that the communication pipe runs from the water main to the boundary of the property and is normally the water company’s responsibility. The supply pipe runs from the boundary, often where there is a company stop tap, to the first fitting inside the building, and that belongs to the property owner.
On a new build, laying the supply pipe across your own land is your job. Affinity asks for it to be laid to the size and material in the cost advice, up to the agreed connection point at the boundary, and to comply with the Water Supply (Water Fittings) Regulations 1999. The simplest route is to use an approved plumber or groundworker who can certify the installation, and you may also be asked for photographs before a connection date is set.
Depth matters too. Water regulations guidance sets a minimum depth of 750 mm and a maximum of 1,350 mm for an underground supply pipe, and going outside that range needs the water company’s permission. On a long plot, that is a lot of trench, and it is far easier to dig while other groundworks are already open.
If an annexe is getting its own supply, it goes through the same process. Affinity fits a meter for each new property it connects, normally in a boundary box at the edge of the property.
Who can dig the connection
The work between the main and your boundary does not always have to be done by the water company. Affinity’s charging arrangements state that you may choose an accredited contractor to do the contestable work rather than asking it to, provided the contractor is accredited under the Water Industry Registration Scheme. You can check a firm’s accreditation on the LRQA WIRS register.
This is where the convertible quote earns its keep, because it shows both options side by side. Firms such as McFadden Utilities, a family-run, WIRS-accredited contractor based in Welwyn Garden City, carry out this kind of work for single homes and plots as well as larger developments: digging and reinstating the trench, laying the new pipe and making the connection once the water company has approved the route. For a self-builder, the practical benefit is having one contractor deal with both sides of the boundary instead of coordinating two separate digs.
The order that saves time
The connection itself is rarely complicated. Delays usually come from doing things in the wrong order. A sensible sequence looks like this:
- Apply to the water company as soon as planning permission is granted.
- When the cost advice arrives, decide whether the water company or an accredited self-lay provider will carry out the work.
- Lay the supply pipe on your own land, at the right depth and to the specified size, while other groundworks are open, and have it certified.
- Request the connection. Affinity says its planning team will propose a date within five days and usually completes new connections within 21 calendar days, unless permits or road closures hold things up.
- Lay driveways, paths and landscaping after the pipe is in, not before.
The last point is the most common and most avoidable mistake. A new driveway laid over the route of a pipe that has not yet been installed is a driveway that gets dug up again.
The short version
A water connection is rarely the biggest cost on a new home, but it is one of the few that depends on someone else’s diary. Start with the water company as soon as you can, read the cost advice for what it actually charges, and get your side of the pipe in while the ground is open. That is what keeps mains water off the critical path.
David Prior
David Prior is the editor of Today News, responsible for the overall editorial strategy. He is an NCTJ-qualified journalist with over 20 years’ experience, and is also editor of the award-winning hyperlocal news title Altrincham Today. His LinkedIn profile is here.
