VS Series
Thames Water v Severn Trent
Same industry, same regulator, very different balance sheets
Severn Trent leads on 3 of the five measures that matter most: turnover, pre-tax profit, profit margin, growth and net assets. Thames Water is the biggest by turnover at £3,757m, against £2,588m at Severn Trent. Severn Trent keeps more of every £100 it takes, £22.76 as pre-tax profit.
The year ends are close enough to compare like for like.
Accounts compared: Thames Water to Mar 2026 · Severn Trent to Mar 2026
Who they are
Thames Water
Thames Water Utilities Limited · 02366661Thames Water is the water and wastewater company for London and the Thames Valley, supplying drinking water and collecting and treating sewage.In brief: water and wastewater · London and Thames Valley · regulated bills · privatised 1989Full profile →Severn Trent
Severn Trent Water Limited · 02366686Severn Trent Water supplies drinking water and collects and treats wastewater for homes and businesses across the Midlands.In brief: water and wastewater · regulated bills · Midlands · owned by Severn Trent PlcFull profile →The Numbers
| # | Company | Turnover | Change | Pre-tax profit | Margin | Employees | Pay per head | Turnover per head | Net assets | Bank and cash | Accounts to | Basis |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Thames WaterThames Water Utilities Limited | £3,757m | +37.2% | £226m | 6.0% | 8,472 | £71,000 | £443,000 | £342m | £557m | Mar 2026 | Group |
| 2 | Severn TrentSevern Trent Water Limited | £2,588m | +16.9% | £589m | 22.8% | 9,805 | £62,000 | £264,000 | £3,308m | £758m | Mar 2026 | Group |
Ranked by turnover. Click any column to sort. The leader on each measure is highlighted. Movements are against each company's own prior year. Pre-tax profit is filed except where marked (est.).
Category winners
Biggest by turnover
Thames Water
£3,757m
Most pre-tax profit
Severn Trent
£589m
Highest profit margin
Severn Trent
22.8%
Fastest-growing turnover
Thames Water
+37.2%
Biggest employer
Severn Trent
9,805 staff
Highest pay per head
Thames Water
£71,000
Most turnover per head
Thames Water
£443,000
Largest net assets
Severn Trent
£3,308m
Most cash
Severn Trent
£758m
The Takeaway
- Severn Trent converts the most of its turnover. Of every £100, £22.76 reaches pre-tax profit, against £6.03 at Thames Water.
- Thames Water is the largest on the top line, £3,757m of turnover, 1.5x Severn Trent's £2,588m.
- Thames Water is growing fastest, turnover +37.2% on its own prior year.
- Severn Trent is the biggest employer with 9,805 people; Thames Water pays the most per head, an average staff cost of about £71,000.
- Severn Trent has the largest balance sheet, net assets of £3,308m.
Who keeps the most of every £100 of sales?
Severn Trent keeps the most: £22.76 of every £100 of turnover becomes pre-tax profit. Thames Water keeps the least, £6.03.
Financing bites hardest at Thames Water: £22.14 of every £100 goes on interest.
Every profit figure here is the one the company filed.
The chart splits each company's turnover into £100: what goes on people, on interest and on everything else, and what is left as profit.
Out of every £100 of turnover
Each column is £100 of that company's own turnover, so companies of any size compare on one scale; the figures are pounds out of each £100, not millions. Companies run from the best margin to the worst. Payroll is staff costs, financing is interest paid, other running costs are everything else, and profit is pre-tax profit, filed or estimated as marked in the table. A loss is not an extra cost: it is the part of the costs that runs past the £100 line, marked with a red bracket. Hover over any segment for its figure.
Who is the biggest, and does the comparison hold?
By turnover the order is Thames Water (£3,757m), Severn Trent (£2,588m).
By headcount, Severn Trent leads with 9,805 employees.
The accounting periods all end in the same month. All are on the same filing basis.
Turnover on the latest filing
Who is growing fastest?
Thames Water grew fastest, turnover +37.2% on its own prior year, ahead of Severn Trent (+16.9%).
Turnover change on each company's own prior year
Who employs the most, who pays the most, and who brings in the most per head?
Severn Trent employs the most, 9,805 people, against 8,472 at Thames Water.
Thames Water has the highest average staff cost, about £71,000 a head; Severn Trent the lowest, about £62,000.
Thames Water brings in the most turnover per employee, about £443,000, against £264,000 at Severn Trent. It says as much about the business model as the workforce: a marketplace or a wholesaler needs far fewer people per pound than a restaurant or a gym.
Who owns each one?
Ownership as recorded on the Companies House register of people with significant control, in the bands the register uses.
Held by Thames Water Utilities Holdings Limited
A company recorded as a person with significant control. 7 outstanding charges on the register.
Who owns Thames Water →
Severn Trent Water Limited · 02366686Held by Severn Trent Draycote Limited
A company recorded as a person with significant control.
Who owns Severn Trent →
What does the full ledger show?
| Measure | Thames Water | Severn Trent |
|---|---|---|
| Registered name | THAMES WATER UTILITIES LIMITED | SEVERN TRENT WATER LIMITED |
| Company number | 02366661 | 02366686 |
| Incorporated | 1989 | 1989 |
| Accounts filed | 3 September 2026 | 10 August 2026 |
| Turnover, prior year | £2,738m | £2,214m |
| Pre-tax profit, prior year | -£1,647m | £398m |
| Staff costs | £605m | £606m |
| Payroll share of turnover | 16.1% | 23.4% |
| Employees, prior year | 7,824 | 8,763 |
| Dividends paid | n/d | £150m |
| Charges outstanding | 7 | 0 |
A figure the filing does not disclose is shown as n/d; a zero in a filing is treated as not disclosed. Rounding: below £0.1m in thousands, £0.1m to £2m to one decimal place, above that to the nearest million.
Thames Water v Severn Trent: common questions
Who is the biggest of Thames Water or Severn Trent?
Thames Water, with turnover of £3,757m in the year to March 2026.
Which makes the most profit?
Severn Trent: £589m pre-tax in the year to March 2026.
Which employs the most people?
Severn Trent, with 9,805 employees in its latest accounts.
Thames Water or Severn Trent: which is bigger?
Thames Water, with turnover of £3,757m against £2,588m at Severn Trent on their latest filings. On margin, Severn Trent keeps more of each £100 as pre-tax profit. The full head to head is in the VS Series. Read the VS page →
Where do these figures come from?
Each company's latest accounts filed at Companies House. Each links to its full Spark Intel profile, which names the filing it comes from.
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