It's literally a drop in the ocean, but the innovative use of a water purification tablet could prove crucial in stemming the spread of Covid-19, especially among SA's poor.

The tiny, chlorine-based effervescent Aquatab is now being punted by humanitarian disaster groups as a potential solution to costly alcohol-based sanitisers.

With thousands of small plastic sanitiser bottles discarded daily, the idea is to refill the bottles with water and add a tablet, creating a long-lasting and potent sanitising solution.

Driving the project, which is being rolled out at taxi ranks on Gauteng's East Rand, is the realisation by NGOs of how quickly hand sanitisers run out and the difficulty taxi drivers have in refilling the dispensers.

The idea has seen religious divides bridged, with Jewish and Christian aid groups partnering on the project, which is being piloted among 300 taxi drivers in Benoni and Boksburg.

Mendy Grauman, director of the Jewish humanitarian disaster aid group Cadena SA, which has partnered with Be Blessed Church, said the tablet was originally designed for water purification.

"Given that its role is purification, it has the potential to provide an effective and cheap solution to costly alcohol-based hand sanitisers.

"The distributors of the tablet in South Africa looked at its use as a sanitiser and explored different options for the best sanitising concentration.

"One tablet to 100ml of water makes a strong enough solution to act as a sanitiser, but the challenge then came down to quantity, with taxi drivers needing sanitisers that would last them for more than a day. Given the high volume of commuters taxi drivers are transporting now, and how they are constantly driving, quantity is crucial."

Grauman said it was discovered that five effervescent tablets added to a 500ml bottle of water lasted taxi drivers, on average, three days. He said there were 32,000 tablets in a box, "which will sustain the drivers for a long time".

"A strip of 10 tablets will create one litre of sanitiser, enough to sanitise the entire taxi and passengers for three days."

Grauman said with Be Blessed Church they were educating taxi drivers about the option.

Darin Fey, MD of Future Strategy, which distributes Aquatab in Southern Africa to humanitarian organisations involved in water-relief projects, said: "In countries affected by Ebola outbreaks, these tablets were used to sanitise hospitals and clinics. While designed for water purification, when used in a higher dosage they work well to kill viruses and bacteria."

He said when it came to getting sanitisers into the field, the tablets were a cheaper option for relief organisations.

Taxi driver Michael Ntini said they were constantly running out of sanitiser, "especially with more people going to work now. It [getting sanitiser] has become a big problem. There is not enough and we can't operate without it.

"This will help. It will be easier. We can now make our own sanitiser. Also, there is enough to clean the inside of our taxis."