South African scientists have developed a high-tech tea bag-like filter that fits into the neck of a bottle and turns polluted water clean as you drink from it.

While it may look like an ordinary tea bag, the small sachet could deliver clean water to hundreds of millions of people in Africa.

Instead of tea leaves, the tea bag-like sack is filled with active carbon granules that can remove harmful chemicals.

Stellenbosch University’s Professor Eugene Cloete says the filter is easy to use in an every day setting.

“They would go to a river; they would scoop up the water from the river. They would insert the filter in the bottle, in the special cartridge that we are busy prototyping, and they would drink the water. It is as simple as that,” he said.

To make the filter, Professor Cloete’s team uses tiny fibres, each about one hundredth the width of a human hair.

They weave them together through a process called electro-spinning.

Professor Cloete says the material is then covered in a thin film of chemicals, which she claims can kill even the nastiest germs.

“I think the most important difference that the filter will make is that it will remove bacteria from the water. Bacteria is a big problem, cholera is a big problem in Africa, and this filter will eradicate cholera basically,” he said.

Waterborne diseases like cholera kill thousands of people in Africa every year.

Last year there were more than 85,000 cases of cholera reported in 10 countries from Mali to Congo and almost 5 per cent of cases were fatal.

UNICEF Australia’s Norman Gillespie says dirty water is at the heart of disease outbreaks.

“Quite often we see it even after natural disasters and emergencies. This is where water supply becomes very unsafe and where people are huddled together either in camps, refugee camps, or in areas of disasters,” he said.

“Then that outbreak spreads very fast indeed. And it’s simply all to do with drinking unsafe water.”

Low-cost solution

Mr Gillespie says the sachet promises to provide easy access to clean drinking water for vulnerable communities, for instance those living near polluted streams.

“Anything that is low cost and easily accessible will have huge benefits. We’ve seen that with treated malaria nets, with micro-nutrient supplements and oral rehydration salts,” he said.

“So an invention like this could have incredible advantages in these situations.”

On a continent where many people live on less than $2 a day, cost is often a barrier to health services, but at just three cents, Professor Cloete says the disposable filters are more affordable than costly infrastructure projects.

And he is working to make them even cheaper.

“We are busy redesigning the filter as we speak so that it might not even look like the original tea bag filter because we can improve it in a number of ways by changing the design,” he said.

Mr Gillespie says current ways of getting clean water into disaster zones are often bulky and impractical and the new filter could offer a portable solution.

“We saw for instance in the Pakistan floods that water supplies were wiped out. The wells are very shallow and easily contaminated,” he said.

“We had to actually get water in trucks and sometimes those trucks were trying to get through impassable roads. So really we need a better solution than that very bulky one and a very costly one would have huge benefits right across the world.”

The tea bag water filter is currently being tested by the South African Bureau of Standards.

If it passes the safety checks, the developer plans to release it to communities in need.