The average household water bill is set to rise by about £13 to £388 a year from April after Ofwat increased prices by 3.5%.
The water services authority said the above-inflation price hike will help pay for about £1,000 investment for every household in England and Wales.
Regina Finn, Ofwat chief executive office, says the authority had prevented water suppliers from enforcing a greater increase.
"We understand there is a huge pressure on household incomes and any rise is unwelcome," she says.
"Inflation is driving these increases. We will make sure customers get value for money, and if companies fall short in delivering their investment promises, we will take action."
She adds there should be £25 billion worth of investment in the water and sewerage network in England and Wales before 2015.
Ann Robinson, director of consumer policy at uSwitch.com, a price comparison site, says: "In total, consumers will now have to find an extra £107 a year to meet the cost of their essential utility bills."
She says consumers using a water meter could save £54 a year.