What is Trimpley?
Put simply, Trimpley increased the amount of money shown in Severn Trent Water’s accounts as legally available for dividends.
Severn Trent says it never used that extra amount to fund dividends.
Having that extra room did not automatically mean dividends would be paid. Severn Trent says it never used the additional capacity created by Trimpley to fund dividends.
The company describes Trimpley as a way of managing differences between the money it earns under the water regulatory system and when that money can be shown as income in its formal company accounts.
Why was Trimpley created?
Severn Trent created the structure in 2017.
The arrangement increased the retained earnings shown in Severn Trent Water’s accounts. In everyday language, this gave the regulated water company additional financial room from which dividends could legally be paid if the other necessary conditions were met.
Severn Trent says:
Trimpley was created to deal with differences between regulatory and company accounting;
it has never needed to use the flexibility provided by the structure;
Trimpley has not affected customer bills, tax or the dividends actually paid; and
its dividends could have been paid without relying on Trimpley.
Ofwat has also said that the structure did not affect customer bills or operational performance and did not support excessive dividends.
These are the positions of the company and regulator.
They do not remove the need for transparency about why the structure remains in place and when it will end.
Is Trimpley common in the water industry?
No other regulated water company reports a similar investment, according to Ofwat.
Ofwat has also confirmed that Severn Trent did not ask it to approve either the Trimpley structure or the later reduction of capital that created additional reserves.
The company did not require the regulator’s approval under its licence. That makes public clarity particularly important. Trimpley is not a standard structure reported across the regulated water sector.
What did Severn Trent tell Parliament?
In June 2025, Severn Trent told the Environment, Food and Rural Affairs Committee that it planned to adopt new accounting rules at the earliest opportunity.
The company said it anticipated doing this during the financial year ending 31st March 2027.
It then gave Parliament a clear assurance:
“When we adopt this new standard, we can confirm that we will dismantle the Trimpley structure.”
The company repeated later in the same letter that it would dismantle Trimpley when it adopted the new standard.
This is an important distinction. Severn Trent did not give Parliament an unconditional promise that Trimpley would be gone by 31st March 2027.
It did, however:
identify the financial year in which it expected to adopt the new rules; and
confirm that it would dismantle Trimpley when that happened.
What has Ofwat now said?
In a written response to Clean River Action, Ofwat said that March 2027 was never an agreed deadline and that there is no formal end date for Trimpley.
That means there is currently no regulator-agreed deadline requiring the structure to be dismantled by March 2027.
The missing deadline creates a serious accountability question. A clear assurance was given to Parliament, linked to a timeframe identified by the company itself, but there is no formal timetable showing when the structure will actually go.
Why does this matter?
This is not simply a technical argument about accounting.
It raises wider questions about:
whether public assurances given to Parliament are properly followed up;
whether regulators require companies to provide clear and measurable timetables;
what happens if a company’s anticipated timeframe changes;
how customers can track whether commitments are being kept; and
who is responsible for securing a definite outcome.
A public commitment should not be allowed to quietly become an open-ended assurance.
If the accounting changes have been delayed, the public should be told. If Severn Trent’s plans have changed, the company should explain why. If the commitment remains in place, customers should be given a clear and updated timetable.
What are we asking?
Clean River Action is asking:
Does Severn Trent still intend to dismantle Trimpley when it adopts the new accounting rules?
Does it still expect to adopt those rules during the year ending 31st March 2027?
If that expectation has changed, when did it change and why?
When will a formal timetable for dismantling Trimpley be published?
What action will Ofwat take to ensure the public commitment is followed through?
If there is no agreed deadline, how will either the company or regulator be held accountable for delivery?
The central issue
Severn Trent told Parliament that it expected to adopt new accounting rules during the year ending 31st March 2027 and confirmed that Trimpley would be dismantled when those rules were adopted.
Ofwat has now told Clean River Action that March 2027 was never an agreed deadline and that there is no formal end date.
A public assurance was given to Parliament, yet there is still no regulator-agreed deadline and no published timetable for dismantling Trimpley.
That is not clear accountability.
When will Trimpley actually go?
Primary documents