Felicity Evans
Money editor, BBC Wales News
People in most parts of Wales are facing a 27% increase in their water bills from April, with the average annual bill going up from £503 to £639.
It marks the start of a five-year period of bill increases from Welsh Water, totalling 42% by 2029-30 - but the biggest rise will happen at the beginning.
A consumer group said there was "an urgent need to bring in a new system of providing help for people who will find it increasingly difficult to pay their bills".
Welsh Water said from April clean water would cost "an average of £1.75 a day" and the overall increases would fund a "68% increase in investment" over the next five years.
Water companies across Wales and England are increasing bills, which they say will lead to more investment to deal with problems like leaks and sewage overflows.
Hafren Dyfrdwy, which serves about 87,000 customers along the Wales-England border is increasing bills by 32% from April taking the average bill from £447 to £590.
But the company said customers "have the lowest bills in Wales and one of the lowest in the UK" and help is available for those struggling to pay.
Each company runs its own system of cheaper rates or capped bills, called social tariffs, for eligible customers.
Welsh Water said it currently supports 150,000 customers with reduced bills and was increasing its financial support packages from £63m to £73m over the next five years.
But Rhodri Williams, deputy chair of the Consumer Council for Water (CCW), called for an end to the "postcode lottery" of support for struggling families.
The CCW has proposed a single system of support for customers across Wales and England.
Mr Williams said that, under the proposed scheme "there would be more money to spend on assistance for customers in Wales" because rates of poverty were higher than in England.
Mum-of-two Bianca Lepore from Cardiff gets her water charge capped by Welsh Water, saving her about £280.
She gets a cheaper bill under the WaterSure scheme because one of her children is disabled.
The NHS worker said the saving "means that I can do more of the meaningful things in life with my children".
She said anyone who is struggling with bills should "reach out to Welsh Water."
"Until you ask, you don't get," she added.
How can I get a cheaper water bill?
Dwr Cyrmu Welsh Water and Hafren Dyfrdwy, offer a variety of schemes for some struggling customers.
- WaterSure caps costs for families who have a water meter, or if they are receiving certain benefits and either have three or more dependent children at home or have someone in the family with a medical condition that increases water use
- HelpU tariff caps bills for households receiving certain benefits and with an income below £18,800 for a family of three or more, or below £17,400 for a family of two. The single person income threshold is £11,600
- If you are already in debt with your water bill, you may be able get financial contributions towards paying it off if you can follow a pre-agreed payment plan
How can I reduce my water costs?
- Consider getting a water meter if you are in a small household - CCW provides a calculator to see if it might save you money.
- If you are already on a water meter think about how you can use less water, and fix any leaks around the house
- Get free water saving devices from Welsh Water to use on taps and shower heads and in toilet cisterns to reduce water usage.
Despite the increases, water bills for each household will vary, depending on factors like the size of the house, whether there is a water meter, and how much water is used.
But Mr Williams said the cost of bills had already impacted many people's budgets.
A survey by CCW found that a quarter of households with a water meter were cutting back on what was considered "essential" water use.
He added that if customers were paying more, water companies "are going to have to improve their performance" in relation to "environmental pollution and leaks being fixed quicker".
Sam James of Welsh Water said it had not taken the decision to increase bills "lightly" but "if people are worried, we can provide help and we encourage people to get in touch with us".
She said the company would be spending much more over the next five years to make their infrastructure more "more resilient" to climate change, delivering a "really ambitious environmental programme and protecting rivers and seas".