How to switch business water supplier

Most businesses have never switched

Quick summary. Every non-household premises in England and Scotland can choose its water retailer. Switching takes two to three weeks, doesn’t interrupt your supply, and happens entirely in the background. This guide walks through the full process from start to finish, what you need before you begin, and what to look for when choosing a new retailer.

In this Guide

1. What actually happens when you switch
2. Who can switch
3. What you need before you start
4. The switching process step by step
5. How long it takes
6. England vs Scotland
7. What to look for when choosing a retailer
8. Common mistakes when switching
9. How much you can save
10. When to switch

You get a water bill every quarter, you pay it, and you don’t think about it again until the next one lands. That’s how most businesses handle water. The idea of switching suppliers doesn’t even cross the mind because, until fairly recently, you couldn’t.

That changed in April 2017 for England and back in 2008 for Scotland. Since then, any non-household premises can choose which water retailer handles its account. And most businesses still haven’t done it.

The switch itself isn’t complicated. It doesn’t involve engineers, it doesn’t interrupt your supply, and it takes about two to three weeks. What holds most businesses back is a general assumption that water is water and there’s nothing to be done about the bill. That assumption is costing them money every quarter they don’t act on it. We run a business water comparison that shows you what’s available for your supply point.

What actually happens when you switch

When you switch business water supplier, you’re changing retailer, not wholesaler. The wholesaler (Thames Water, Severn Trent, United Utilities, Yorkshire Water, or whoever covers your region) still owns and maintains the pipes. Still treats the water. Still handles the sewerage network. None of that changes.

What changes is the company that sends you a bill, reads your meter, and handles your account if something goes wrong. That company is your water retailer. Before market opening, you had no choice. Now you do.

Your physical water supply isn’t touched during the switch. No one visits the property. No one touches the meter. The retailer changeover happens entirely in the background through MOSL, the central market operator. You won’t notice anything different about your water. The only change is the name on the bill and the rates on it.

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Who can switch

Every non-household premises in England has been able to choose its water retailer since 1 April 2017. In Scotland, the market opened nine years earlier, in April 2008.

“Non-household” covers essentially every business, charity, and public-sector building. If your premises has a commercial water supply (rather than a domestic one), you’re eligible. That includes offices, shops, restaurants, factories, warehouses, schools, hospitals, and churches. If you’re a sole trader working from home on a domestic supply, you can’t switch. If you’re a business operating from commercial premises, you almost certainly can.

There’s no minimum size requirement. A one-person office above a shop has the same right to switch as a multi-site industrial operation. The savings scale with consumption, obviously, but the option is there regardless.

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What you need before you start

You don’t need much. The process is designed to be straightforward and most of what’s required is on your existing water bill.

Your SPID number. This is your Supply Point Identification Number. It’s the unique reference for your water supply point, like an MPAN is for electricity or an MPRN is for gas. It’s printed on your water bill. If you have separate water supply and sewerage, you’ll have two SPIDs, one for each. If you can’t find it, a broker or comparison service can look it up from your address.

Your current consumption. How much water you use (in cubic metres) over a year. Again, this is on your bill. If your bills are estimated rather than read, your actual consumption might differ from what’s been billed, but the estimate gives a starting point for quotes.

Your current contract details. Are you in a fixed-term contract? When does it end? Is there a notice period? If you’re out of contract (or never signed one after market opening), you can switch whenever you want. If you’re in-term, you’ll typically need to wait until the contract expires unless there’s an early termination clause.

A letter of authority (if using a broker). If you’re comparing through a broker or comparison service like us, you’ll sign a short letter of authority. This gives us permission to approach retailers on your behalf, request live quotes, and manage the switch process. It doesn’t commit you to switching. It just lets us act on your behalf. There’s a full explanation in our business water letter of authority guide.

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The switching process step by step

Once you’ve decided to switch, the process runs like this.

You choose a new retailer. Either by comparing quotes yourself (contacting retailers individually) or through a comparison service that pulls quotes from multiple retailers at once. The second option is faster because retailers compete for your supply point in a single round rather than you chasing individual quotes.

You sign the new contract. Once you’ve picked the retailer and tariff that works for your business, you sign their contract. This is usually a one to three year fixed agreement, though some retailers offer shorter terms.

Your new retailer handles the transfer. They submit a switch request through MOSL (the central market system). Your old retailer is notified. You don’t need to contact your old retailer yourself. You don’t need to cancel anything. The new retailer does it all.

The switch completes. Within two to three weeks of the request being submitted, your account transfers to the new retailer. They take over billing from the next meter read. Your old retailer issues a final bill up to the switch date.

That’s it. No disruption, no site visit, no change to your water pressure or quality. The whole thing happens on paper and in systems.

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How long it takes

The standard switching timeline is 10 to 20 working days from when the switch request is submitted to MOSL. Add a few days either side for paperwork and you’re looking at two to three weeks from decision to completion.

If your existing contract hasn’t expired, you’ll need to wait until it does (or until the notice period allows you to leave). Some retailers will let you sign a new contract now with a start date aligned to your old contract’s end date, so you don’t miss the window.

The one thing that can slow things down is a disputed meter read at the point of transfer. Both the old and new retailer need to agree on the closing read. If there’s a disagreement, MOSL has a process for resolving it, but it can add a few days.

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England vs Scotland

The process is functionally the same in both countries. The main differences are regulatory.

In England, the market is regulated by Ofwat. The central market operator is MOSL. Retailers are licensed by Ofwat and must meet its standards for service and billing.

In Scotland, the market is regulated by the Water Industry Commission for Scotland (WICS). Scottish Water is the sole wholesaler for the entire country. Retailers are licensed by WICS. The market has been open longer (since 2008) so it’s slightly more mature, with more competition among retailers.

If your business operates sites in both England and Scotland, you can use different retailers in each country. Some retailers operate in both markets, which might simplify things if you want a single relationship, but there’s no requirement to use the same one.

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What to look for when choosing a retailer

The rates matter, but they’re not the only thing worth considering.

Price per cubic metre. This is the headline rate and the obvious comparison point. It varies by retailer and by wholesale region (because different wholesalers charge different amounts for the infrastructure layer). Get quotes specific to your SPID, not generic rate cards.

Standing charges. Some retailers roll infrastructure costs into the unit rate. Others break them out as a separate standing charge. Compare the total annual cost, not just the unit rate.

Billing accuracy. A retailer with slightly higher rates who sends accurate, timely bills can work out less expensive than one who estimates for months then sends a large catch-up invoice.

Customer service. How easy is it to get someone on the phone? How quickly do they resolve disputes? If your water supply has an issue, you’ll be dealing with your retailer first, even though the wholesaler handles the physical fix. A retailer that acts as an effective intermediary is worth something.

Contract length and exit terms. Standard contracts run one to three years. Check the notice period and what happens at the end. Auto-renewal clauses exist in water contracts just as they do in energy. Set a reminder for the notice window so you don’t get rolled onto terms you didn’t actively choose.

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Common mistakes when switching

Not checking the contract end date. If you’re still in a fixed-term contract, you can’t switch without an exit fee (or waiting it out). Check before you start comparing.

Focusing only on unit rate. The cheapest per-cubic-metre price doesn’t always produce the lowest annual bill. Standing charges, drainage charges, and surface water charges all affect the total.

Forgetting about sewerage. Your water supply and sewerage are often on the same bill but can technically be with different retailers. Make sure quotes cover both supply and sewerage unless you’re specifically looking to split them.

Missing the notice window. Fixed-term contracts typically require notice before the end date (often 30 to 90 days). Miss it and you might roll onto out-of-contract rates or an auto-renewed term.

Assuming you can’t switch because you’re in Scotland. Scottish businesses have actually had this right longer than English ones. The process works the same way.

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How much you can save

It depends on what you’re currently paying and what’s available on the open market. Businesses that have never switched since market opening in 2017 are often still on default rates set by their original retailer. Those defaults weren’t set competitively because there was no competition when they were established.

The size of the gap between default rates and competitive rates varies by region and by retailer. Some businesses find the difference covers a meaningful chunk of a quarterly bill. Others find it’s more modest. The only way to know what’s available for your specific supply point is to compare live quotes. It takes a few minutes and costs nothing.

We run a business water comparison that pulls quotes from across the market for your supply point. You see what’s available, and nothing happens unless you actively choose to switch.

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When to switch

Any time you’re out of contract, or approaching the end of one. There’s no particular season where rates are better or worse (water pricing doesn’t have the seasonal volatility that gas and electricity do).

If your contract is approaching its end date, start comparing a month or two before the notice deadline. That gives you time to get quotes, review them properly, and make a decision without rushing.

If you’ve never switched and you’ve been on the same retailer since 2017 (or 2008 in Scotland), you’re almost certainly on rates that haven’t been tested against the open market. Worth a look.

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“Switched our water supplier through Clearsight with zero hassle. Genuinely couldn’t believe how easy it was.”

M. Sheridan, business customer · ★★★★★ on Trustpilot

Clearsight Energy helps UK businesses compare, understand, and move to better water and energy contracts. Compare business water suppliers