The £4.2bn cost of the Thames Tideway Tunnel project was to be funded entirely by Thames Water customers. This has angered some customers who believe the company has benefited from tax breaks sanctioned by industry regulator, Ofwat, when it was allowed to add debt to its balance sheet, reducing its tax payments while allowing its shareholders to receive dividends – money some customers feel should have been spent on the Thames Tideway Tunnel. Thames Water maintained it has done nothing unusual by raising debts to reduce tax bills and that this was following conventional practice. It said the money raised was used for essential maintenance and upgrade works, although some have asked questions about how Thames Water paid so little corporation tax at the same time as distributing dividends to its shareholders.