THAMES WATER’S mismanagement is “beyond a joke” and billpayers should not have to shoulder the burden, campaigners charged after reports surfaced that the firm is plotting a 56 per cent rise in bills.

The water supplier is expected to publish a revised business plan to regulator Ofwat.

In its original plan in October, the firm said that it would raise customer bills by 40 per cent and fund an investment programme worth £18.7 billion to fix its crumbling network, which saw sewage spills increase five-fold last year.