Welsh Water has pledged to achieve net zero carbon emissions by 2040.
It currently generates 23% of its own energy needs using wind, hydro and solar, procuring the rest of its energy from 100% renewable sources.
It has set an aim to increase this to 35% energy self-sufficiency by 2025 and to slash its carbon emissions by 90% by 2030.
It has committed to investing more than £80 million in research and innovation to transform wastewater services in the next five years.