Customers of Welsh Water could see their annual bills reduced by £22 a year, under proposals from the not-for-profit company.
The utility firm, headquartered in Nelson, has submitted its proposed business plan for 2020 to 2025 to water industry regulator Ofwat.
If approved the company, which serves more than three million customers across most of Wales, Herefordshire and parts of Deeside and Cheshire, has promised to spend £2.3 billion over the five years on its infrastructure.
Welsh Water Chief Executive Chris Jones said: “As a not-for-profit company, our customers’ interests are at the heart of everything we do.
“The plans aim to strike the right balance between investment for the future, and making sure bills remain affordable for customers today. With better service, more help for the vulnerable, increased investment and lower bills, we are confident that this plan offers even better value for money for our customers in the years ahead.”