Denbighshire County Council and Welsh Water are encouraging residents to check if they qualify for a money-saving scheme.
The HelpU tariff caps water bills for eligible households, potentially saving them up to £200 annually.
Despite this, only 2,253 Denbighshire households currently benefit from the scheme, suggesting many are unaware of its existence.
To address this, the council and Welsh Water are sending emails and letters to residents, highlighting the available support and to encourage applications.
To qualify for the HelpU tariff, a household member must receive at least one means-tested benefit, such as Universal Credit or Pension Credit.
Additionally, the combined annual household income must be on or below the threshold for the household size.
This is £11,600 for one occupant, £17,400 for two occupants, and £18,800 for three or more people in the household.
Rebecca Price, customer services director at Welsh Water, said: "We are committed to putting the needs of our customers first to support the most vulnerable in society.
"We urge Denbighshire residents to get in touch to find out how we can help you with your payments and discuss the best options moving forward."
The scheme is part of a broader initiative to make water bills more affordable, as research by water services regulator Ofwat found nearly one in four households were struggling with water bills.
Councillor Gwyneth Ellis, lead member for finance, performance, and strategic assets at Denbighshire County Council, said: "Everyone should have access to affordable water.
"I would encourage all residents in Denbighshire to check if they are eligible for cheaper water bills.
"Many people are not aware they are entitled to these schemes so it’s important we highlight them to ensure residents are maximising their household incomes.
"If you’re struggling to pay or are worried about any of your bills, please contact Citizens Advice Denbighshire for free, confidential advice."
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