Wrexham-born swimmer Pardoe, part of Team GB at the Tokyo and Paris Games, has so far raised nearly £8,000 for Surfers Against Sewage.

But he believes water quality in the UK is a source of national shame having faced many bouts of illness throughout his open-water swimming career.

Illnesses from bacteria such as E. coli, commonly caused by sewage in the water, have become all too regular. Water quality monitors providing real-time data were used during his three-lake swim.

It is why he insists it is important to use his platform “for something bigger than just winning a medal”.

“Sport is a thing of national pride and we’re one of the best nations per capita across the world,” he said.

“We’re always finishing inside of the top five in the Olympic Games but we’re lagging behind in many areas of water pollution.

“I was fortunate enough to start open water swimming when I was 12 but we’re seeing a constant closure of open water venues across the country,” he said.

“More and more rivers, lakes are being deemed unsafe to swim due to sewage discharge.

“I have to take all sorts of precautions, like a shot of Pepto-Bismol before and after every swim,” he said.

“I use precautionary antibiotics and have to clean my face and hands immediately after getting out of the water before touching anything.”