Holding a Water Company Quote? What Each Charge on It Actually Pays For

A water company quote for a new connection rarely arrives as a single number. It usually comes as several lines: an infrastructure charge, an environmental component, a connection charge and a few fees. Most people look straight at the total. The individual lines are more useful, because they tell you which parts are fixed, which depend on your site, and which you can still influence.

Here is what each one pays for, using the published 2026/27 charges from two of the water companies serving London and the Home Counties, Affinity Water and Thames Water.

The infrastructure charge: your share of the wider network

The infrastructure charge is not for your pipe. It is a one-off charge per property towards reinforcing the wider network as new homes are added. Affinity Water's 2026/27 charging arrangements describe it as reflecting "broadly the expected additional load placed on our network by the connection of premises".

The calculation behind it is simpler than most people expect. Affinity takes its network reinforcement costs of £35,527,851 and divides them by the 57,760 connections it expects, which gives a charge of £615 per plot for 2026/27.

Because the charge is built from each company's own reinforcement costs and connection forecasts, it varies a great deal between companies. Thames Water's 2026/27 charging arrangements set its water infrastructure charge at £1,575 per property, more than twice Affinity's. Nothing about your site changes that figure. The same house can attract a very different charge depending on which side of a water company boundary it sits. Where a property also needs a sewer connection, Thames adds a separate wastewater infrastructure charge of £780.

The environmental component, and how to earn it back

Since April 2025, quotes have carried a newer line. Affinity explains that under Ofwat's Environmental Incentives Common Framework, all developer customers must pay an environmental component charge to fund incentives, and that companies must offer at least one environmental incentive to promote water efficiency.

For 2026/27 the component is £127 per household property at Affinity and £150 at Thames. Affinity's charging arrangements state that the money "is used solely to fund the Environmental Incentives". In other words, it is not a general environmental levy. It is a pot that pays back developers who build water-efficient homes.

Affinity runs three tiers. The Basic incentive requires every fitting to meet a set specification, including a dual-flush WC of no more than 4 and 2.6 litres, showers of no more than 7 litres a minute and baths of no more than 170 litres. The Enhanced and Premium tiers go further, requiring usage of 81 to 90 litres per person per day, or 80 litres or less, shown through the company's water efficiency calculator.

The practical point is timing. These choices are made when the bathrooms and kitchen are specified, long before the connection is booked, so they are worth raising with the architect or builder early.

The connection charge: where your site comes in

The connection charge pays for the physical work of joining your pipe to the main, and it is the line that depends on your site. Thames prices a standard 25/32 mm connection at £6,470 in a road, £4,570 in a private road or footpath, £2,520 in unmade ground and £1,110 where there is no excavation or the customer excavates, all plus VAT, with pipe laying charged per metre on top.

The gap between the top and bottom of that range is not the connection itself. It is the digging, the traffic management and the reinstatement of whatever surface lies between the main and your boundary.

Application and design fees sit alongside this line. At Thames they are paid when you apply, before the quote arrives, and cover processing the application and designing the connection.

Flats and conversions

If you are converting a building into flats, the infrastructure charge is not always a simple multiple of the number of units. Thames uses a "relevant multiplier" for residential properties on a single shared supply under a common billing agreement. It adds up loading units for every fitting, from 1 for a WC or wash basin to 4 for a bath, and compares the result with an average property.

For properties under a common billing agreement, that multiplier can come out above or below 1.00. Thames' own worked example gives a block of 20 flats a multiplier of 0.96, so each flat's infrastructure charge comes out slightly lower than a standard house's.

What changes if someone else does the dig

Much of the connection work is contestable. Thames treats service connections up to 63 mm as contestable, and Ofwat confirms that the customer may choose their own contractor to do the work, which is known as self-lay. The contractor needs to be accredited under the Water Industry Registration Scheme, which you can check on the LRQA WIRS register.

What self-lay does not change is the per-property charges. The infrastructure charge and environmental component are charged per property, so they stay on the bill whoever builds the connection. Only the connection work changes hands, which is why it pays to compare the two routes line by line rather than total against total. For a company-by-company comparison of Affinity, Thames and Anglian Water, McFadden Utilities sets out what each of those charges covers in its guide to new water connection costs.

Five questions to ask when the quote arrives

1. Is the infrastructure charge applied to the right number of properties, and does a multiplier apply if the scheme is flats?
2. Does the environmental component line show any incentive you could qualify for, and what would the fittings need to be?
3. Which surface is the connection priced on: road, footpath, unmade ground or no excavation?
4. How many metres of pipe laying are included, and does that match the actual distance to the main?
5. Which lines are contestable, and what would an accredited contractor charge for the same work?

The short version

The fixed lines on a quote are published every April and apply across that water company's area. The site lines are where the choices sit. Reading the two separately is the quickest way to work out whether a quote is high because of where you are, or because of what has to be dug.