Why BioSand

The water situation in rural Cambodia deeply affects the poverty that is so prevalent in the communities we serve. To address this situation we needed a highly effective, low cost solution that could provide clean water consistently for years. The scale and scope of the water situation in Cambodia is what lead us to implement us to the BioSand technology.

We chose BioSand filters because:


BioSand filters are the most efficient and economical solution. BioSand technology is open source and royalty free, allowing us to build as many as our budget will allow. The materials to construct the BioSand filter are all available locally and are very affordable.

A home filter unit can be constructed for $60 and will provide enough clean water for a family to drink, wash, and bathe with.

Clean water pipes

The main components of the home filter box are concrete mix, sand and PVC pipe. We purchase all of these in the communities where the filters are constructed and used. This fuels the local economy and reduces transportation costs for the materials.

The sand and gravel that make up the filter medium are mined from two mountain quarries in Kampong Speu province outside of Phnom Penh. Sourcing our filter medium in country is better for the environment and provides jobs for the local economy.

Requires Community Investment

Each family that receives a BioSand filter actively invests in the process of bringing that filter to their family, and each community actively invests in bringing the filter to their school.

Each family must invest $5 to receive a filter. They must provide the transportation to move the filter from the construction site to their home, participate in the construction and they must participate in the community education programs to ensure their filter is maintained and serves them well.

Schools must provide a roof structure to cover the filter system and a water storage tank for the latrines.


The BioSand filter medium we use in our filters lasts for decades, requiring only regular maintenance.

To clean the filter the family will stir the surface of the BioSand medium to release the trapped particles into the standing water. This water containing the particles is then removed from the filter. Then the surface of the BioSand layer is leveled and the filter is ready use again.

Our home filter bodies are made of concrete and will last indefinitely. The first filters we constructed are still in operation today. Our school filters tanks are made from recycled materials and have a natural life of 15 years or more.

BioSand Filter Technology Effectively Removes Pathogens and Contaminants.

Slow sand filters have been shown to remove almost all the disease-causing organisms found in water. The BioSand filter has proven as effective as traditional slow sand filters, in both laboratory and field tests. The filter has been tested by various government, research, and health institutions, as well as by non-governmental organizations.

Overall, these studies have shown that the BioSand filter removes:

How BioSand Technology Works

The BioSand filter is made of a concrete shell on the outside with layers of sand used for water purification on the inside. The filter works through a combination of mechanical and biological processes. Water is filtered by sand particles and a biological layer that develops on the surface of the water, this layer is known as the biofilm.

When water passes through the filter, the organic material it carries is trapped at the sand’s surface and forms the biological layer. Over several weeks during the filter’s initial use, micro-organisms colonize this layer and the water passing through the filter provides them with oxygen and food. These micro-organisms then remove contaminants in the water through predation. The rest of the filter structure further purifies the water through trapping, adsorption and the natural death of biological contaminants. See the diagram below for an illustration of this.

The BioSand filter can purify between 20 and 60 liters per hour and can last for decades with simple maintenance.

A Brief Tour of Our BioSand Logistics Center

Where Can We Take You Next?