How Does the Filter Work?
Bio-sand filters were developed by Dr. David Manz over 30 years ago. He designed them based on larger scale versions that had been used on a community level for decades. His goal was to create a household sized version that could be used in developing countries and by people living off grid so they could filter contaminated source water. To date, bio-sand filters are being used in many developing countries around the world because they’re an effective and cost efficient way to provide access to treated water.
We love the bio-sand filter for many reasons. It’s a simple, yet effective technology. When installed and used correctly a bio-sand filter can remove up to 99.99% of all disease causing pathogens – the microbes that make us sick. The small percentage of remaining pathogens is something that our bodies can fight off through our immune systems. The filters are made from simple materials – sand, gravel and cement. There are plastic versions of the filter, but we’ve chosen the concrete version for it’s durability, and because building it in country means we can have a constant supply on hand to meet the demand. It provides full time employment for local Haitians and builds into the local economy through the purchasing of materials to construct the filters.
The filters are simple to use and they don’t require any replacement parts, so there is no ongoing maintenance cost for the family using it. Bio-sand filters can filter most source water, so people can use the water they have available to them. Many of the communities we work in are very rural and far away from any option of buying treated water, so this is a key thing.
Bio-sand filters are a great filtration model for Haiti because they work with the challenges faced by many people here. They’re simple, easy to maintain, made from local materials, and are durable. It’s what we call an “appropriate technology”.