A researcher from Stellenbosch University in South Africa claims to have developed a water filter the size of a tea bag. It thus can be fitted under the cap of a bottle. This significantly reduces the cost and inconvenience of water quality, as reported by BBC News
"We cover the tea bag material with nano-structured fibres, and instead of tea inside the tea bag, we incorporate activated carbon.
"The function of the activated carbon is to remove most of the dangerous chemicals that you would find in water."
He says that the function of the fibres is to create a filter where harmful bacteria is physically filtered out and killed.
The BBC does not mention what quantity and speed of water can be filtered by a single bag. Those are the usual metrics but each bag is meant to be used only for a single serving just like tea.
The inventor, "past executive vice-president of global network of water professionals the International Water Association and a member of Coca-Cola's global panel of water experts", emphasizes the importance of decentralized solutions to help those most in need of water security.
A water security risk index of 165 nations, released by UK-based risk consultancy firm Maplecroft in June found that African and Asian nations had the most vulnerable water supplies, judged by factors such as availability of drinking water, demand per capita and dependence on rivers that flow through other countries. [Professor Eugene] Cloete adds that more than 90% of all cholera cases are reported in Africa, and 300-million people on the continent do not have access to safe drinking water.
"The 'tea bag' filter can show the way forward, as it represents decentralised, point-of-use technology. "It can assist in meeting the needs of people who live or travel in remote areas, or people whose regular water supply is not treated to potable standards. "As it is impossible to build purification infrastructure at every polluted stream, we have to take the solution to the people," he notes.