Every water firm in England and Wales under investigation over sewage spills

Ofwat opens cases against Severn Trent and three others, days after they faced criticism over huge bill rises

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The water regulator is taking action against four more water companies, including Severn Trent and United Utilities, meaning every wastewater company in England and Wales is under investigation over sewage spills.

Ofwat said it had served formal notices on Dr Cymru Welsh Water, Hafren Dyfrdwy, Severn Trent and United Utilities, asking them to provide evidence for its investigation into companies' wastewater management in England and Wales.