Households struggling to pay their water bills are to receive help through new social tariffs, according to the government.
Water companies will be given the power to reduce bills for the most vulnerable customers under the tariffs set out in new government guidance, Deputy Prime Minister Nick Clegg will announce from the Rio+20 Conference in Brazil on Friday.
An estimated 2.4 million households have difficulties meeting the costs of their water bills.
Water companies are bound by regulator Ofwat's licensing conditions, leaving them unable to reduce bills for certain customers. But the new guidance will free them to make cuts for struggling customers.
Clegg said: "We're clearing the way for water companies to give some much-needed help to the millions of people who struggle to pay their water bills. If you're struggling to make ends meet, not paying for essential utilities isn't an option but it can mean making tough choices elsewhere, like sacrificing healthy meals for the family or new school books.
"We've already announced tough new measures to see gas and electric bills fall by up to £100 a year. This will see struggling families save more.
"Water companies can now begin to consult their customers on how to ensure the most vulnerable households receive extra support."
The average water bill in England and Wales is £376, with 11% of households spending more than 5% of their disposable income on their bill.
Environment Secretary Caroline Spelman said: "Many people on low incomes have been struggling to pay their water bills, and these new measures will give them much-needed help.
"Water companies now have the chance to work with their customers to find a solution that works for them, and I hope to see that solution in place as soon as possible."
Companies are also expected to support vulnerable customers with advice on how to use water more efficiently, guidance on whether installing a water meter could save them money and referrals to debt and benefits advice.
The government is planning to propose further reforms to the water industry later this summer in a draft Water Bill.