Thousands take to London streets demanding cleaner water

Environmental activist and singer Feargal Sharkey and adventurer Bear Grylls were among those planning to join The March for Clean Water, which was backed by groups including Greenpeace, the Wildlife Trusts and British Rowing.

Protesters are demanding reviews of water regulator Ofwat and the Environment Agency along with stricter enforcement for water companies who break existing pollution rules.

River Action said that there were around 15,000 marchers, who were encouraged to wear blue and to bring a sample from a body of water close to their heart.

Many wore elaborate costumes, while others held signs reading "tides not turds", "cut the crap" and "water for life".

Jenny Linford, a 61-year-old food writer, told AFP that it was "disgusting what has happened to our waters since the water companies were privatised.

"It's absolutely obscene that Britain's rivers and lakes and seas are having more sewage pumped into them.

"We're here because we want to speak up for water... and just say to politicians 'please act'," she said, adding that the issue was a factor in the Conservative Party's defeat in the July election.

The new Labour government last month set out legislation that will give regulators powers to issue harsher penalties, including prison sentences, to polluting water companies and their executives.

Lewis Pugh, endurance swimmer and ocean advocate, told AFP the march was "an opportunity to tell government that we really do need them to sort out what's happening in our rivers.

"When you allow agricultural runoff to go into rivers, or industrial waste or plastic pollution to go into rivers, not only do you kill the river and everything in it, but it goes into our oceans and does exactly the same thing," he added.

Water UK, the industry's trade association, acknowledged that the current system "is not working".

"It is too complicated, too slow and is not delivering for people or the environment," said a spokesperson.

"We cannot delay upgrading and expanding vital infrastructure any longer and need Ofwat to reconsider its approach," it added.