Water companies across the region said they welcomed the rights of the protesters to express their views.
They have said they are investing heavily in infrastructure and new technology to improve water quality but state that other factors, such as weather, agriculture and runoff, also impact river and coastal health, and that progress depends on shared responsibility.
Wessex Water said most coastal waters in its area were rated excellent by the EA, adding that it was investing in AI monitoring and major infrastructure upgrades to improve river health.
Dr Nick Mills, director for environment and innovation at Southern Water, said improving river and sea health was a priority, with major investment in storm overflow reduction, AI and a £1.5bn Clean Rivers and Seas Plan.
South West Water said that despite heavy rainfall it has cut overflow spills and spill durations through a £760m investment plan. It said while “there’s more to do… the direction is clear: Fewer spills, shorter durations and investment where it matters most”.
Thames Water said it was prioritising river health by “delivering the biggest upgrade across our wastewater assets in 150 years” over the next five years. It said it was committed to “seeing waterways thrive” adding: “But we can’t do it alone… clean, safe and healthy rivers are a shared responsibility.”