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Compare Business Water Suppliers in London
Compare licensed water retailers for London businesses, supplied wholesale by Thames Water.
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Home / Areas we cover / London
Last updated August 2026
Areas we cover
Compare Business Water Suppliers in London
London is unusual. Around 95% of central and Greater London is supplied wholesale by Thames Water; the remaining western and northern suburbs (parts of Hertfordshire, Essex and Surrey-side LBs) are supplied by Affinity Water. Both wholesalers set different supply rates, and the open-market retailer you choose can only offer pricing within the wholesaler’s standard tariff , what they compete on is retailer margin, billing accuracy, account-management quality, and the audit work behind your invoices.
You can switch retailer. London businesses have had that right since the market opened in April 2017. Most never have. This page covers where London business water costs come from, how the wholesaler/retailer split actually works in the capital, and where overpayment usually hides on a London bill.
| Wholesale supply | Most of central and Greater London is supplied wholesale by Thames Water. |
|---|---|
| Contracting | Single sites can contract directly with retailers, and multi-site operators can contract centrally across the whole estate. |
| Biggest savings levers | Tariff reviews on defaults never renegotiated, surface water drainage checks and billing audits. |
| Market opened | England in 2017 and Scotland in 2008. |
| Licensed retailers | Around 20 are licensed by Ofwat to supply non-household water. |
Where the money goes
Why London businesses pay more for water than they should
Your wholesaler is set by postcode and never changes. Thames Water owns the pipes and sets the wholesale rate. The retailer is the part you choose, and it competes on the retail layer, billing accuracy and the audit work behind your invoices.
London businesses overpay on water for three reasons specific to the capital: Thames Water’s wholesale tariff is the most complex in England, surface drainage charges on dense central-London buildings rarely match where rainwater actually goes, and the new Thames Tideway charge sits on every bill but most operators have not factored it into their renewal calculations.
London is unusual. Around 95% of central and Greater London is supplied wholesale by Thames Water; the remaining western and northern suburbs (parts of Hertfordshire, Essex and Surrey-side LBs) are supplied by Affinity Water. Both wholesalers set different supply rates, and the open-market retailer you choose can only offer pricing within the wholesaler’s standard tariff , what they compete on is retailer margin, billing accuracy, account-management quality, and the audit work behind your invoices. On top of that, every London business water bill now carries a Thames Tideway tunnel charge, the long-standing surface water drainage charge that’s often miscalculated on dense urban buildings, and a Greater London Authority business-rate-linked levy on some larger sites. None of these are obvious from a glance at the invoice, and most have refunds available going back six years.
Where it shows up
The five areas London businesses overpay
Where London businesses overpay and why it matters.
Surface water drainage on dense central buildings
Charged on building footprint regardless of where rainwater actually goes. Many central-London buildings drain to private soakaways, internal drainage to combined sewers, or attenuation systems. Rebate-able with a drainage survey.
Thames Tideway tunnel charge applied flat-rate
Every Thames Water customer pays this; some retailers absorb part of it, others bill it as a clear pass-through. Worth comparing.
Default Thames Water tariff that nobody renegotiated
When the market opened in 2017, most London businesses stayed on Thames Water’s default retailer (Thames Water Commercial). That tariff was rarely the cheapest then; less so now.
Affinity Water boundary unrecognised in contracts
Some North-West London businesses are wholesale-supplied by Affinity Water rather than Thames. A retailer offering both wholesalers may have sharper rates than your default.
Estimated meter readings on hard-to-access central sites
Multi-tenant buildings in the City and Canary Wharf often have meters that haven’t been physically read for 18+ months. Estimates drift upward; actual readings recover the difference.
Results
Case studies
Surface water drainage audit across the estate uncovered £35,364 in refunds and £8,800 a year in ongoing savings.
Worth knowing
Eligibility and how the market works
Every non-household premises in London is eligible to switch retailer through the open market run by Open Water. England opened in April 2017 and Scotland has been open since 2008.
Most of central and Greater London is supplied wholesale by Thames Water. Parts of north-west London, areas of Hertfordshire and west Surrey are supplied by Affinity Water. Your wholesaler is determined by postcode, not by the retailer you choose. The retailer can change; the wholesaler can’t. The wholesale network is run by Thames Water and Affinity Water, and wholesale charges are the same whichever retailer bills you.
The market
Switch water supplier for your London business
Yes. England’s non-household water market opened to competition in April 2017 and Scotland’s opened in 2008, so every London business can choose a different water retailer. Wholesale supply still comes from your regional water company; only the retailer (the company that bills you and reads your meter) changes.
The 12 retailers below are all licensed by Ofwat to supply non-household water. Pricing, service and sector experience vary from retailer to retailer.
Choose your route
Routes to procurement
Three ways London businesses typically bring a new water contract in. Each comes with its own trade-off between control, effort and how sharp the price lands.
Direct with a retailer
The business signs straight with a licensed retailer. Best for a single site that wants a sharper rate. You handle the comparison and the switch yourself.
Estate-wide contract
Multi-site operators across the surrounding area can put every site on one central contract with one retailer, even where sites sit in different wholesaler regions.
Broker-led market test
A water broker compares the market for you, handles the paperwork and manages the switch from start to finish. Nothing changes on site.
Why choose The Business Water Shop
- Award-winning independent brokerage, not owned by or tied to any water retailer.
- Rated 5 stars on Google and 5 stars on Trustpilot by UK businesses.
- Experts with experience in business water for businesses across London and the surrounding area.
- We compare quotes from up to 14 licensed retailers.
- We handle the whole switch, from the comparison and paperwork to the supplier contact.
- One point of contact for multi-property portfolios.
Questions
London business water FAQs
Can London businesses switch water supplier?
Yes. Since the non-household water market opened to competition in April 2017, every business in England , including every London business , can choose a different water retailer. Wholesale supply still comes from Thames Water (most of London) or Affinity Water (parts of north-west London). Only the retailer changes.
Who supplies wholesale water to my London business?
Most of central and Greater London is supplied wholesale by Thames Water. Parts of north-west London, areas of Hertfordshire and west Surrey are supplied by Affinity Water. Your wholesaler is determined by postcode, not by the retailer you choose. The retailer can change; the wholesaler can’t.
Can a London business switch water supplier?
Yes. Since the non-household water market opened in April 2017, every business in England can choose a different water retailer. The retailer is the company that bills you, reads your meter and handles account questions. The wholesaler (Thames Water or Affinity Water in London) still owns the pipes and the supply.
What is the Thames Tideway tunnel charge?
A pass-through charge on every Thames Water customer’s bill that funds the new sewer tunnel running under London. It’s a wholesale charge, not something your retailer sets. Different retailers display it differently on the invoice (some absorb part of it, most pass it through clearly) but the underlying rate is the same.
Do all water retailers cover London?
Yes. The licensed retailers can supply Thames Water and Affinity Water wholesale areas. The differences worth checking are: which retailer has a dedicated London account team, which absorbs vs passes-through Tideway, and which offers the sharpest unit rate for the volume tier your business sits in.
What is the surface water drainage charge and can London businesses claim it back?
It’s a charge for rainwater that lands on your property and enters the public sewer. London buildings frequently route rainwater to private soakaways, attenuation ponds (newer developments), or combined sewers via internal drains rather than surface drains. Where rainwater isn’t reaching the public surface drainage network, the charge can be partially or fully refunded up to six years back.
How long does a switch take in London?
Two to six weeks from contract signature. The supply doesn’t change , the wholesaler still runs the pipes and the meter. Only the retailer (your billing provider) changes. There’s no installation, no engineer visit, no service interruption.
