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Biosand Filter, a life-saving invention from Calgarian David Manz, turns 30

The Biosand Filter is celebrating thirty years of providing clean drinking water to communities in the developing world.

The idea of designing a water filtration system small enough to be installed in rural homes came to Calgary engineering professor David Manz after a trip to South Africa in the late 1980s.

"I was familiar with all the water treatment technology of the day. One of the things that always came to mind was this thing called slow-sand filtration. Slow-sand filtration is really elegant. It was cheap, simple to operate, but a lot of them failed … And I couldn't figure out," he said.

Manz returned to Calgary and began further researching water projects in the developing world.

"I realized what the criteria should be, he said. "It had to be functional in a household.  In other words, they had to be able to use it. It had to be people oriented."

"I couldn't just take the big technology, the old technology, and put it into this miniature technology. This is where the innovation came in. I figured out why these things were failing, and I figured out how to overcome that problem."

Manz’s original design has been modified over the past three decades, but the principle remains the same.

The filter container, made of concrete or plastic, contains layers of specially selected and prepared sand and gravel.

The sand removes pathogens and suspended solids from contaminated drinking water. 

The type of bacteria and other micro-organisms which grow in the top two centimetres of sand eat many of the pathogens in the water, improving water treatment.

Using one is as simple as pouring contaminated water in the top and watching clean water run out the bottom.

While the filter removes close to 99 per cent of the pathogens in drinking water, it cannot purify water that has been chemically polluted.


After developing and testing the Biosand Filter, Manz made a decision that would ultimately change the lives of tens of millions of people worldwide; he patented the filter and then opened the patent for royalty-free humanitarian use.

"The Biosand Filter means no more illness, and no more sickness in people's homes. It means opportunity. It means kids are going to school, it means adults are going to work. It means that they have time to do other things with their time, like make healthy lunches and go out and get jobs and for kids to play," said Taryn Meyers, director of global services for the Centre for Affordable Water and Sanitation Technologies (CAWST).

"It's tremendous what the Biosand Filter has done.

"It's pretty incredible that this invention has an open patent, and that CAWST has taken it on to deliver that information to the world.

"It has truly changed the lives of people, and it has been such a goodwill gesture from our fellow Calgarian."

CAWST was founded in 2001 with the goal of increasing the humanitarian distribution of the Biosand Filter.  

It is both a charity and an licensed engineering firm, providing training and advice to agencies working to improve water quality and sanitation around the world.  

The agency estimates it has provided the information and support for the installation of over 1.7 million Biosand Filters worldwide.

"That's not bad, that's how I see it, but it's just the beginning," said Manz.

"It's a good track record . So now, let's do hundreds of millions. and that's really what I believe. Maybe billions." Top Stories

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