The UK business water market in 2026: every Ofwat-licensed retailer, ranked

How the market is structured

Since April 2017, all English non-household water customers — businesses, charities, schools, public-sector buildings — have been able to choose their water and wastewater retailer. The market is split into:

• Wholesalers — the regional water companies that own the pipes and treat the water. You don't choose your wholesaler; it is fixed by your geography. Wholesalers include Severn Trent, Thames Water, United Utilities, Yorkshire Water, Anglian Water, Northumbrian Water, Wessex Water, South West Water, Southern Water, Affinity Water, Welsh Water, and others.
• Retailers — the licensed entities that send your bill, manage your account and resolve queries. You can choose any retailer, anywhere in England.

The household market in England remains regulated, with no choice of retailer. Scotland has had its own competitive non-household market since 2008.

The major retailers in 2026

Some of the most active business water retailers in the UK in 2026:

• Castle Water — the largest non-household retailer in the UK, serving over 350,000 sites. Strong on multi-site portfolios and the public sector. Customer service has historically been mixed; significantly improved over the last two years.
• Business Stream — owned by Scottish Water Business Stream Holdings; deep Scottish heritage now extended into England. Strong digital reporting tools.
• Water Plus — joint venture between Severn Trent and United Utilities. Default retailer for many customers in the Midlands and North West who haven't actively switched.
• Wave Utilities — joint venture between Anglian Water and Northumbrian Water. Strong on public sector frameworks.
• Everflow — independent specialist retailer focused on SMEs; competitive pricing on smaller sites.
• SES Business Water, Pennon Water Services, Cobalt Water and others fill out the long tail.

How to compare retailers

The wholesale element of your bill — typically 80% of the total — is fixed by your geography and is identical regardless of which retailer you choose. So the meaningful comparison is on:

1. Retail margin (the price difference between wholesale and what you pay)
2. Service level — billing format, query response times, online portal quality
3. Multi-site capability if you operate more than one location
4. Ancillary services — leak alerts, AMR (automated meter reading) integration, water-efficiency advice

Hidden charges to watch for

• Surface water drainage — many sites pay for this without using it. If you have permeable car parks, soakaways or no surface drainage connection, you may be due a rebate.
• Trade effluent — if you discharge anything other than clean rainwater, you need a consent. Charges are based on the strength and volume of effluent. Many sites have either over- or under-paid for years.
• Default tariff drift — non-switched accounts often sit on the highest retailer margins. The cost of being on default is rarely visible until you tender.

Action checklist for finance and facilities teams

1. List every site, postcode and water meter (SPID — Supply Point Identification) you operate.
2. Pull six years of consumption data from your current retailer (or the wholesaler if your retailer can't provide it).
3. Tender across at least four retailers, anonymised, on identical commercial terms.
4. Audit for leak allowance, surface water rebate, and trade effluent classification.
5. Sign with the retailer that wins on a weighted price + service score — not just headline price.

Or send the list to us, and we'll run all five steps for you. More on our water service.