Thousands of homes will save money after a regulator ordered water firms to knock £150million off household bills.
Water regulator Ofwat has ordered 11 water companies to cut water bills from next April and said they were "falling short" of its expectations.
Ofwat said these firms had missed its targets on things like pollution, sewer flooding and water supply breakdowns.
Water firms that missed Ofwat's targets, like Southern Water and Thames Water , will have to return money to customers.
The exact refund per household will vary.
But other water firms have the green light to increase bills - such as United Utilities, Wessex Water and South Staffs Water.
The 11 water firms who have been told to cut customers' bills are:
- Affinity Water
- Anglian Water
- Dŵr Cymru
- Hafren Dyfrdwy
- Northumbrian Water
- SES Water
- South East Water
- South West Water
- Southern Water
- Thames Water
- Yorkshire Water
Ofwat chief executive David Black said: “When it comes to delivering for their customers, too many water companies are falling short, and we are requiring them to return around £150million to their customers.
“We expect companies to improve their performance every year. Where they fail to do so, we will hold them to account.
"The poorest performers, Southern Water and Thames Water, will have to return almost £80million to their customers.
"All water companies need to earn back the trust of customers and the public and we will continue to challenge the sector to improve.”
A Southern Water spokesperson said: "As laid out in our annual report, we recognise that Southern Water has not always met expectations in recent years but are now in a position to deliver significant change for our customers and the environment.
“This includes investing £2billion (circa £1,000 per household) between 2020-25, more than our regulatory allowance, to significantly improve our performance.
"We are on-track to reduce pollutions by 40% compared to 2021 with much still to be done to maintain this to the end of the year, and we are also industry leading in self-reporting.”
Warren Buckley, customer experience director at Thames Water, said: “It’s one of the biggest priorities of our plan to turn around our performance and our shareholders have recently approved an additional £2billion into the business so we can improve outcomes for customers, leakage and river health.
"We know we have more work to do to improve customer experiences across our services and we’re already accelerating the customer elements of our turnaround plan to improve our position."
“We’re determined to do better, and while we’re heading in the right direction, we know there is a long way to go.”
The average UK home pays £419 for water over 12 months, with the typical bill rising £4 this year .
Around 1.1million people need help paying these bills, according to trade body Water UK earlier this year.
This will rise to at least 1.4million by 2025.
Around £200 of the average bill goes to paying for water, and the remaining £219 for sewerage costs.
How to get help paying water bills
You can contact your water supplier if you need help with bills.
Since the start of the Covid-19 pandemic more than 100,000 hard-up customers have been granted payment breaks to give them breathing space.
Water suppliers can also cut bills for customers on low incomes or refer them to organisations that can help with bills.
The Watersure scheme also caps water bills if you are on benefits or need to use a lot of water due to having several children or medical reasons.
For a full list of financial support available, click here.
People in some areas will get help with water bills without needing to apply.
For example, those supplied by South East Water have bills capped if they are on low incomes, as the water firm checks council lists of eligible households.
Homes getting water from Severn Trent can get discounts of up to 90% on their water bills if they have a household income of less than £16,385.
