Thames Water is continuing the fight to add an extra £29 to the annual average household bill.
Earlier this year it proposed to increase customer bills by 8% in 2014, putting the demand down to “significant” extra costs from taking on an extra 40,000 kilometres of private sewers and charges and increases in bad debt.
Regulator Ofwat however rejected the request last week as it did not believe the evidence given by the water firm justified an increase in bills, which currently stands at £354 a year.
The decision was subject to a period of technical consultation and allowed Thames Water time to appeal before a final decision scheduled in November.
A spokesperson from the water company said: “We have submitted further evidence supporting our application, made in August, for a temporary adjustment to prices in 2014/15. We await Ofwat’s final decision, due next month.”