UK households are facing significant water bill increases, with some customers receiving bills up to 47 per cent higher than expected.
The average annual water bill in England and Wales will rise by £123 from April - around £10 a month - but millions face even steeper increases.
Thames Water customers have expressed shock at higher than expected annual increases as the struggling water group "front-loads" the impact of permitted regulatory increases.
The utility, which supplies about a quarter of the UK population, was allowed by water regulator Ofwat to raise bills by 35 per cent by 2030.
However, some customers have been flummoxed to receive bills that are 47 per cent higher than a year ago.
Ruth Hawkins said: "It's beyond scandalous for Thames Water to implement such huge financial increases."
The Hackney resident with a two-bed flat was not prepared for her annual bill to increase by 47 per cent from £432 to £639 this year.
The average water bill increase by around £10 a month
GETTYDifficulties fitting water meters in blocks of flats means Thames Water estimates her water consumption using the "assessed household charge".
This year, the company has raised its estimates of water usage for customers who aren't metered. The fixed annual charge for all water customers has also gone up to £191.71, which means it makes up a larger part of bills for people in smaller properties.
The difference comes from Ofwat's plan, which spreads out increases over five years but applies them earlier to help pay for important infrastructure upgrades.
Future percentage increases should be smaller each year until 2030, though water companies can adjust prices to keep up with inflation.
Bill rises for the next five years in England and Wales are being front-loaded, with a big increase this April so that spending on new infrastructure, such as new reservoirs, can get going.
Thames Water said: "For us to continue to deliver billions of litres of clean water and take wastewater away from millions of homes, it's vital that we invest in our network and infrastructure."
Southern Water customers will see a 47 per cent increase to £703 a year while Hafren Dyfrdwy and South West Water bills are rising by 32 per cent.
Bournemouth Water customers will also face a 32 per cent increase. Yorkshire Water is raising bills by 29 per cent.
Other factors, such as whether a customer is metered and how much water they use, means the bill changes will vary considerably.
Michael Martin, a financial adviser, said the annual bill for his home in Wimbledon had increased by 45 per cent this year to £1,186.
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He told the Financial Times: "Since 2018, the total increase in my water bill is not far off the performance of the S&P 500 index."
Thames Water says it's already helping around 450,000 customers pay their bills, and by 2030, one in 10 households could be receiving support.
The company offers a 50 per cent discount on bills for customers on low incomes who can prove their bill is more than five per cent of their net annual income.
A single occupier tariff is available for customers without water meters who can prove they live alone, potentially reducing annual bills by about 10-20 per cent. However, this discount is not extended to single parents.
Ofwat is set to announce that bills will rise by more than a fifth of current charges in the next five years (Stock)
PAThames Water added: "We would encourage any customer that is concerned about their ability to pay to reach out to us."
Water companies have committed to set aside more than £4bn to fund social tariffs over the next five years.
Consumer groups are warning the rise means more households will fall into debt. Almost half of households in England and Wales struggled to pay for their water over the past 12 months.
More than eight per cent of households or 2.5 million people were already in payment arrears, according to Ofwat research published in January.
Mike Keil, Consumer Council for Water (CCW) chief executive said: "These rises will heap considerable pressure on millions of customers who are already having to make difficult choices.
"Customers want to see investment in improving services and cleaning up our rivers but that can't come at an unbearable cost to struggling households."
The CCW said this was the largest rise in water bills since privatisation 36 years ago.
