How to switch business water supplier

Can your business switch water supplier

Eligibility is the most common question. The honest answer is “almost certainly, if you’re in England”, and the geography matters more than people realise.

The business water market in England opened to competition in April 2017 under the Water Act 2014. Any non-household customer in England can switch water retailer. Scotland opened earlier, in 2008, and runs under a separate framework. Wales and Northern Ireland don’t currently have open water markets, which means businesses there can’t switch retailer at all. That’s not a quirk of paperwork. It’s the underlying market structure.

Within England, the eligible base is wide: offices, retail units, restaurants, hospitality, manufacturing, warehouses, hotels and most other commercial premises. Charities and public sector bodies qualify on the same basis. The only meaningful condition is being on a business (non-household) meter rather than a domestic one. If you’re not sure which you’re on, the supply point identification number on your bill answers the question.

What you need before you start

A water switch needs less paperwork than an energy switch, but the one piece nobody can find on the first try is the SPID.

SPID stands for Supply Point Identification number. It’s the water equivalent of an MPAN on electricity or an MPRN on gas. Every water bill carries one. If you can’t see it, your current retailer can read it out over the phone. You’ll also want a year’s worth of bills if you can pull them, your current annual water and wastewater spend, the retailer name and account number, the meter serial number (on the bill or stamped on the meter itself), and the registered business name and address.

Multi-meter sites have a SPID per meter, so list them all. New occupants need a tenancy agreement, lease or business rates bill. The water letter of authority is the single document that lets a broker pull quotes on your behalf without you having to repeat the same information to every retailer.

How the water market is structured

This is the section worth reading even if you skip everything else. The single biggest source of confusion in business water is the split between wholesaler and retailer.

The wholesaler owns and maintains the pipes, treatment works and the rest of the physical infrastructure. Names you’d recognise: Thames Water, Anglian Water, Severn Trent, Yorkshire Water and the rest. Your wholesaler is determined by where your premises sit on a map. It doesn’t change when you switch.

The retailer is the company that bills you, manages your account, handles queries and runs the customer-facing services. That’s the part you can change. Clearsight works with retailers including Business Stream, Brightwater and Wave, among others, depending on which fits the customer’s profile best. Ofwat regulates the market overall and sets the wholesale price; the retailer adds a margin for the services they provide.

The practical implication of all this: switching retailer doesn’t change your water pressure, your water quality, or who fixes the pipes when something goes wrong. Only the bill changes hands.

Step-by-step: how to switch

The mechanics, once you’ve got the SPID and the bills.

1. Confirm eligibility. England or Scotland, non-household, on a business meter. If you’re in Wales or Northern Ireland, the market isn’t open and there’s nothing to switch to.
2. Find your SPID. On the bill. If you can’t see it, ring the current retailer and ask them to confirm it. Multi-meter sites have a SPID per meter.
3. Pull together your usage history. Twelve months of bills if possible. This is also the point where any obvious billing oddities (sudden jumps, estimated reads, unusual standing charges) start to surface.
4. Compare retailers. The water market is less transparent than energy, and broker access matters more here than on the energy side. A broker pulls quotes from the retailers most likely to suit your usage profile.
5. Review the quote properly. Look at the unit rate per cubic metre, the standing charge, the contract length, and any service-level commitments. Some retailers offer consolidated billing across multiple sites.
6. Sign with the new retailer. They handle the notification to your existing retailer and coordinate the cutover with the wholesaler.
7. Take a meter reading on switch day. Photograph it. This pre-empts billing disputes.
8. Wait roughly four to six weeks. Supply doesn’t change. Pipes don’t move. The wholesaler keeps doing what it was already doing.

Why timing matters in 2026

Water has done what most businesses assumed only energy did. Prices are climbing, and they’re climbing fast.

Wholesale water prices are rising about 21% on average for 2025/26, taking effect from April 2026. The regional picture is uneven. Southern Water bills are up around 47%. South West Water is up around 32%. Other regions sit lower but still well above the inflation rates anyone is used to budgeting against. Across the previous five years, wholesale water prices climbed roughly 42% in total. The cost line that businesses used to set and forget is no longer behaving that way.

The driver behind most of this is the Price Review 24 (PR24) settlement. Ofwat approved a £104 billion infrastructure investment programme covering 2025 to 2030, recovered through wholesale prices over that period. The investment is funding leak reduction, sewer upgrades and new resource resilience after years of under-investment. The cost has to come from somewhere, and it’s coming from bills.

For businesses that haven’t reviewed water in the last twelve months, the practical position is straightforward. You’re almost certainly paying above market on the retailer margin, and you’re absorbing the wholesale rise without any offsetting work on the retail side. Switching now locks in a competitive retail rate before further increases hit. It doesn’t insulate you from wholesale movement (nothing does, that part is regulated), but it removes the part you can control.

Tenancy and meter edge cases

A few situations come up often enough to be worth flagging.

New occupant. Water doesn’t switch automatically when tenants change. The new occupant must register with the existing retailer first, providing evidence of occupation (tenancy agreement, lease, business rates bill).

Landlord pays the bill. If the lease puts the water account in the landlord’s name and they recharge the tenant, the tenant can’t switch directly. That’s a conversation with the landlord first. See our change-of-tenancy guide.

Multiple meters on one site. Each meter has its own SPID. A broker can run a multi-meter switch as a single process.

Shared supply. Some industrial and retail premises share a meter with neighbouring units. A switch needs agreement from everyone sharing the supply point.

Unmetered premises. A small number of business premises are still on rateable value charging. Request a meter installation before switching. Metered rates are almost always cheaper.

Where a water audit fits

A switch handles the retailer rate. A water audit handles everything else: meter accuracy, leak detection, billing errors and consumption patterns the bills don’t surface on their own.

The reason audits matter is that water bills are unusually error-prone. Estimated reads, mis-allocated meters, drainage charges applied to premises that don’t drain into the sewer, surface water charged where there’s no surface drainage to charge for. None of these get fixed by a retailer change. They have to be found and challenged.

For most businesses the right sequence is to switch first to lock in a fair retail rate, then run an audit on the back of it. The audit benefits from the cleaner data the new account brings, and any refund work can be pursued retrospectively against the historical period.

A few specific things audits commonly find. Surface water drainage charges applied to a roof that drains into a soakaway rather than the public sewer. Trade effluent charges left running on an account after a process changed. Meter sizes that don’t match actual usage, where a smaller meter would carry a lower standing charge. Inherited overcharges from a previous occupant, sitting on the account undetected because no one had reason to question them. None of these are exotic. Most premises that haven’t been audited in five or more years carry at least one of them.

Water terms worth knowing before the conversation gets technical

SPID (Supply Point Identification number). The unique reference for each water supply point, like an MPAN for electricity. Every meter on your site has its own SPID.

Wholesaler. The regional company that owns the pipes and supplies the water (Thames, Anglian, Severn Trent, etc.). They sell wholesale to retailers and don’t bill business customers directly.

Retailer. The company that bills you and manages your account. Business Stream, Brightwater, Wave and others. You can switch retailer.

Deemed contract. The default tariff you fall onto if no contract is in place. Almost always the most expensive option.

Surface water drainage (SWD). The charge for rainwater running off impermeable surfaces (roofs, hard standing, car parks) into the public sewer. Often calculated on a banded site assessment that’s wrong.

Trade effluent. Wastewater from commercial activity. If your premises run a kitchen or process water, you may need a separate trade effluent agreement.

Letter of authority. Permission to act on your behalf with retailers and wholesalers. Doesn’t commit you to switching, just lets a broker pull quotes and review your account.