How Using Biosand Filters Is Helping Aquagear Solve the Global Water Crisis

How Using Biosand Filters Is Helping Aquagear Solve the Global Water Crisis

Our Mission at the Aquagear Foundation is to help provide clean water to the nearly 2 billion people who lack access to safe water at home as a means to end water scarcity in our lifetime.1 While lack of access to safe water is a global crisis, it is a solvable one. Through our Foundation, for every filter purchased, we provide six months of clean water by installing biosand water filters in developing communities.2

One of the questions we receive most frequently at the Aquagear Foundation is: What is a biosand filter? Our customers are often curious to know how they work and how they make an impact.

Here are answers to some frequently asked questions about our program, as well as insight into how every Aquagear purchase you make improves the lives of people around the world who are in need of clean, safe drinking water:


How exactly does the program work?

From the beginning, we decided to focus our efforts on helping families in Sub-Saharan Africa - specifically in Tanzania and Uganda. That’s because this area has the largest number of water-stressed countries on the planet. 

In Tanzania, 26 million people - almost half of the population - don’t have access to clean water, 8 in 10 people don’t have a decent toilet, and more than 3,000 children under 5 die from diarrhea caused by dirty water each year.3 In Uganda, approximately 23 million people - about 3 in every 5 - don’t have access to clean water, and more than 4,500 children under the age of 4 die from diarrhea each year.4

Using local labor, Aquagear installs biosand water filtration systems in the homes of families living in these areas. For many families, this is the first time they’ve ever had access to clean, healthy, drinking water in their homes. 


What is a biosand filter?

For more than 200 years, communities around the world have been using traditional slow sand filters to purify water.5 

The first documented use of sand filters to purify water dates back to the early 1800s when the owner of a bleachery in Scotland developed an experimental filter so he could sell his product surpluses.6 Engineers working for private water companies refined his process throughout the next two decades, and ultimately were able to develop the first treated public water supply in the world in London. 

In 1974, the World Health Organization published a document written to encourage the use of slow sand filtration, especially in developing countries. “In recent years, there has been a tendency to assume that slow sand filtration is an old-fashioned method of water treatment that has been completely superseded by rapid-gravity and other high-rate filtration techniques,” the document reads. “This idea is definitely mistaken. Under suitable circumstances, slow sand filtration may be not only the cheapest and simplest but also the most efficient method of water treatment.”7

The biosand filter (BSF) of today is an adaptation of these traditional slow sand filters. 


How do biosand filters work?

The biosand filters we use today have evolved since people started using them 200 years ago. They are smaller and are built in a way that does not require water to continuously flow, which makes it suitable for installation in people’s homes.8

The container, which can be made of plastic, concrete, stainless steel, or any other nontoxic waterproof container,  is filled with layers of prepared gravel and sand that are able to remove pathogens from water. A thin layer of bacteria and microorganisms grows in the top 2 cm of sand, creating a ‘biolayer’ on which the microorganisms live. BSFs are designed to create the optimal environment for the types of microorganisms that can kill pathogens. After about one month of use, the microorganisms in the biolayer stabilize and provide consistent pathogens removal, making it safe for use.9

Because you can use any kind of water in biosand filters, including well water, rain water and water from ponds and rivers, people who are suffering from water scarcity in the most vulnerable areas are able to use whichever water source is closest to their home. This greatly reduces the time and energy a family needs to spend collecting water. 

Contaminated water can be poured into the top of the filter. The water slowly drips through the gravel and sand and flows out of a tube on the side of the container. The biosand filters Aquagear installs are able to filter approximately 6 liters of water per hour. 

Source: CAWST (Centre for Affordable Water and Sanitation Technology)


What impact do biosand filters have? 

There are two main reasons why we choose to use biosand filters to advance our humanitarian work addressing the global water crisis: They are easy to make and maintain and they are extremely effective.

All of the materials needed to make biosand filters are locally available. Additionally, they are simple to use and to maintain for the families who rely on them for healthy drinking water. A proper working biosand water filter will remove:

  • 100% of parasites and worms
  • 98.5% of bacteria
  • 70-99% of viruses, and
  • Nearly all turbidity.

Studies show that biosand filters have a long-term impact on the health and well-being of those who have access to them. One study conducted by University of North Carolina’s Gillings School of Global Public Health found that plastic biosand filters achieved a 97% reduction in E.coli bacteria, significantly reducing diarrheal disease.11 Another study conducted by the University of Birmingham found that over a three month period, 93 percent of filters tested produced acceptable drinking water.12 

While clean water is something many of us in the United States are accustomed to and perhaps take for granted, for most families who receive our biosand water filters, having clean water in their homes is life changing.


  1. Peace, Dignity and Equality on a Healthy Planet. (n.d). Retrieved from United Nations: Global Issues, Water
  2. Aquagear Foundation. (n.d). Retrieved from Aquagear.
  3. WaterAid: Tanzania. (n.d). Retrieved from WaterAid.
  4. WaterAid: Uganda. (n.d). Retrieved from WaterAid.
  5. Biosand Filter. (n.d). Retrieved from CAWST (Centre for Affordable Water and Sanitation Technology.
  6. Slow Sand Filter. (n.d). Retrieved from Wikipedia.
  7. Huisman, L., Wood, W.E. (1974). Slow Sand Filtration. World Health Organization, Geneva. 
  8. What is a Biosand Filter? (n.d). Retrieved from CAWST (Centre for Affordable Water and Sanitation Technology.
  9. What is a Biosand Filter? (n.d). Retrieved from CAWST (Centre for Affordable Water and Sanitation Technology.
  10. What is a Biosand Filter? (n.d). Retrieved from CAWST (Centre for Affordable Water and Sanitation Technology.
  11. C. E. Stauber, B. Kominek, K. R. Liang, M. K. Osman, M. D. Sobsey. (2012). Evaluation of the Impact of the Plastic Biosand Filter on Health and Drinking Water in Rural Tamale, Ghana. International Journal of Environmental Research and Public Health.
  12. Summary of BSF Efficiency Testing Globally. (2009) Retrieved from Serving our Neighbor (SON)