Actor Darius Campbell was left fighting for his life after drinking dirty water from River Thames.
"I drank the water for the video and raised the funds but when I went to Glasgow to see my mum for her birthday, I collapsed. It turned out I had a cerebral oedema where your brain swells bigger than your skull.
"Dad saved my life. He got me to hospital. They diagnosed it quickly," Campbell told The Daily Record newspaper.
The former "Popstar to Operastar" contestant had contracted an inflammatory virus from drinking the water taken from next to sewage outlet on the Thames, leading to bacterial meningitis, reports femalefirst.co.uk.
Campbell's mother Avril was having chemo and radiotherapy for breast cancer at the time her son collapsed in 2015.
He is a founding ambassador of non-profit organisation Fresh2o along with actress Keira Knightley and Formula One racing driver Lewis Hamilton. The charity was set up to dig wells in Africa using profits from portable water filters.
Following his illness, he feared the filter he had been promoting in the demo video – which removes 99.9 per cent of known water-borne pathogens, bacteria and viruses – was faulty. But it emerged that Campbell had been given a bottle without a filter.