Writing in The Daily Telegraph, Ofwat Chairman Jonson Cox, has voiced his concern over water profits and taxation.
He said: "It has also been alleged that some companies use shareholder loans to avoid UK taxation.
"At the same time, hard-pressed customers have seen annual bills rise by 13.5pc since 2010-11, while their incomes have fallen.
"I agree that the dichotomy between profits and the prices charged to customers raises business, regulatory and moral questions."
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