A £10bn investment from water companies to stop sewage spills will be paid for by customers through “modest increases to their bills”.

Ruth Kelly, chair of Water UK, told Sky News that water firms will provide a “huge multi-billion down-payment” to start “the biggest transformation project since Victorian times”.

She added: “The way the system works is that over the lifetime of the assets, customers do pay that money back in modest increases in their bills.”

She said that over the last ten years water bills have fallen for the average customer and “research shows us that customers are prepared to pay a little bit more to see this sort of investment undertaken”.

It comes amid outrage over the large bonuses and dividends paid to water company bosses despite huge levels of untreated sewage being pumped into the UK’s rivers due to a lack of investment.

Earlier, industry body Water UK pledged to invest £10 billion to clean up their act and said campaigners were “right to be upset” as it issued an apology.

She added: “