Mikkel Vestergaard Frandsen started to think how he could put the family company to good use for the people of Africa. The result was LifeStraw, a cheap, portable personal water purifier, cited by Forbes Magazine in 2006 as "one of the 10 things that will change the way we live".

Made of polystyrene, the 31cm long, 2.9cm diametre, 150g tube, which looks like a flute and can be hung around the neck, uses filters to kill or remove 99.9 percent of waterborne bacteria and 98.7 percent of waterborne viruses, and requires no electricity or spare parts during its year-long lifetime, powered by sucking alone. It costs about US$4 and has a purification volume of 700l. The product contains a special halogenated resin that kills bacteria and viruses on contact.

"It turned out to be a giant hit and we ended up selling 23 million of these pipe filters to the Carter Center," Vestergaard Frandsen spokesman Peter Cleary told IRIN by telephone.

Now the Vestergaard Frandsen Group will start rolling out a stationary LifeStraw Family version that will provide clean drinking water for up to 18 months.

It is estimated that 1.1 billion people lack access to safe drinking water and that 1.8 million die annually from preventable water-borne diseases such as diarrhoea, cholera, typhoid and e-coli.

There are 200,000 LifeStraw units in use in dozens of countries in Africa, the Middle East and Asia today, purchased and distributed by partner groups such as the Red Cross, the UN Children's Fund (UNICEF), Rotary International and IMA World Health, a Protestant Christian organisation, according to Cleary.

Long-term limits

However, its long-term potential is limited, according to some. Paul Hetherington, a spokesman for the charity WaterAid UK, told IRIN: "It is something that may well have very useful applications in an emergency scenario. But it's not a development tool, it doesn't really solve the problem of getting water to people.

"This is a good interim stopgap in an emergency where there's plenty of water but it's contaminated, but it's not a long-term solution," he added, citing the need for digging boreholes and tapping springs.

Sarah Dobsevage, programme development officer of WaterAid America, also took the longer-term view. "It is not a sustainable option for poor communities in developing countries to attempt to treat and purify water," she told IRIN.

"Sustainable activities relating to water quality that communities can carry out are the prevention of pollution of their water resources by fencing off catchments, preventing agricultural activities, keeping animals and children away from sources," she said. "It is more sustainable to prevent pollution than it is to treat polluted water."

IMA began distributing LifeStraws on an acceptance test basis in the eastern Democratic Republic of Congo (DRC), where cholera is endemic, with a consignment of 250 in 2005, reporting that 95 percent of recipients said they liked them and hoped they would become available. IMA is now scaling up its activities with LifeStraw.

But IMA project chief Larry Sthreshley cautioned: "The individual LifeStraws have only a limited role in solving Africa's drinking water problem. It takes a fair amount of sucking power to use the straws so it is not appropriate for small children," he told IRIN in an e-mail from the DRC.

He also pointed out that LifeStraw was unable to filter out amoebas and giardia, a debilitating intestinal parasite, saying that this limited its usefulness and appeal.

Fighting parasites

Cleary said the company was working on the giardia problem, which is very complex because the parasites are microscopic. "Our product is not successful against that but we are hopeful that future generations of the product will be able to filter out giardia. But that is a great technological challenge for us and I would not like to put a timeline on it," he told IRIN.

As for the question of children, he said that when LifeStraw is first used the filters are dry and it takes significant sucking power to draw water through, but once the parts become moist, it flows very easily. So parents should use the device first to get the water flowing and then get the children drawing from it.

IMA is already looking to the next generation. "We are most excited about the LifeStraw Family product," Sthreshley said. "It protects against viruses, bacteria and cysts, and is cheaper to use. I think there will be a big demand for this product once it goes into production."

LifeStraw Family is designed to filter 10,000l of water in the home, enough for 18 months, according to Cleary.

Based on the same principle as LifeStraw Personal, it works by pouring water into a bucket, from which it flows through a small hose into the LifeStraw filter device, which is fitted with a small tap. However, it also would not protect against giardia.

Price will depend on how many are bought by the humanitarian partners - $20 apiece for up to 500 sold, and $17 each for a purchase of between 500 and 3,000.