What is Biosand Water Filter

The Biosand Water Filter

The BioSand Filter (BSF) is an adaptation of the traditional slow sand filter, which has been used for community drinking water treatment for almost 200 years. The BSF filter will remove harmful bacteria from water that leads to diarrhea, dehydration, joint pain, liver problems, and a host of other health complications. The BSF has been tested repeatedly for more than 15 years and has proven itself to be capable of removing:

More than 98% of E. coli bacteria
More than 97% of fecal coliform bacteria
100% of protozoa and helminthes
Up to 90% of organic and inorganic toxicants
Greater than 75% of iron and manganese


The BioSand Water Filter produces safe, clean potable water that is clear, no smell, and tastes better.

Water is poured into the top of the filter as needed, where a diffuser plate placed above the sand bed dissipates the initial force of the water. After traveling slowly through the sand bed, the water then passes through a bed of gravel and collects in a pipe at the base of the filter. At this point, the water is propelled through plastic piping encased in the concrete exterior and out of the filter for the user to collect. It should be used with a safe water container with a tight fitting lid and either a narrow mouth or a spigot so that water is poured from the container.

Removal of Contaminants

Contaminants are removed through a combination of biological and mechanical processes. When water is poured into the top of the filter, the organic material it is carrying is trapped at the surface of the fine sand, forming a biological layer. This biological layer matures over one to three weeks, depending on the volume of water put through the filter and the amount of nutrients and micro-organisms in the water.

A healthy biological layer requires both fresh food and fresh oxygen. Fresh food is supplied through regular use of the filter. The filter should be used at least twice a day to maintain optimum results. Fresh oxygen is infused through the shallow water that rests above the sand when the filter is not in use.

Four processes remove pathogens and other contaminants in the Biosand filter:

    1. Mechanical trapping: Sediments, cysts and worms are removed from the water by becoming trapped in the spaces between the sand grains. Over time the spaces become smaller, enabling the filter to trap smaller particles sooner in the sand bed. The filter can remove some inorganic compounds and metals if they are attached to other materials or each other.
    2. Adsorption or attachment: Viruses are adsorbed or become attached to the sand grains. Once attached, they are metabolized by the cells or are inactivated by antiviral chemicals produced by the organisms in the filter. Certain organic compounds are also adsorbed in the sand and thus removed from the water.
    3. Predation: The microorganisms within the biological layer consume bacteria and other pathogens found in the water, thereby providing highly effective water treatment.
    4. Natural death: Food scarcity, less than optimal temperatures, and a relatively short life span will cause pathogens to die off and become nutrients for other micro-organisms.


Like any other household appliance, the BioSand Water Filter requires regular care and maintenance to ensure lasting effectiveness. The outside surfaces and the inside of the lid should be cleaned with soap and water regularly, with special attention to the spout where insects and dirty fingers may deposit contaminants.

Continued use of the filter causes the pore opening between the sand grains to become clogged with debris. As a result, the flow rate of water through the filter decreases. Though this does not reduce the ability to remove contaminants, the slow flow rate is likely to frustrate the user.

To clean the filter, the surface of the sand must be agitated, thereby suspending the sediment in the standing layer of water. The dirty water can then be easily removed using a small container. The process can be repeated as many times as necessary to regain the desired flow rate.&nsbp;

A group of researchers from the Mindanao Center for Research and Development Cooperative (MCRDC) presented a paper entitled BIOSAND FILTER ON ACCESS TO SAFE DRINKING WATER IN THE RURAL COMMUNITIES OF THE PHILIPPINES: AN IMPACT EVALUATION at AIT Conference Center of the Asian Institute of Technology in Bangkok, Thailand on September 19 and 20, 2011.

The paper implies that BSF as an innovative technology for access to safe drinking water provides more benefits to rural poor households in the communities in the Philippines. It shows that the benefits of owning a biosand water filter encompasses the socioeconomic,environmental factors that affects the daily life of an individual.

Below are some helpful facts based from the study conducted:

Health Benefits

  • The biosand water filter have eliminated common contaminants such as iron, copper, lead, which are toxic in long term exposure by 100%.
  • It also successfully removed other inorganic contaminants such as manganese, zinc, and arsenic have been at an average of 75.00%, 54.90%, and 83.33% respectively.
  • The prevention of waterborne diseases reduced or eliminated the hospitalization costs.
  • The annual total health benefit of the household for the utilization of BSF is at Php10,082.06 or US$240.05

Social Aspect Benefits

  • 89.6% said that they regard the filter as a water system that will provide security from any water contamination in their community.
  • In terms of social cultural adaptation (90.6%), they said that BSF does not disrupt their cultural beliefs, norms and practices; in fact, it helps improve social relationships among members of the household.
  • BSF does not violate customary essence of clean water to any activities that involves religious beliefs and BSF do abides and respects with the cultural practices of the community in terms of political structure, power, and authority.

Environmental Benefits

  • BSF could possibly aid in the defense of the environment by mitigating CO2 emission due to fuel wood for boiling of water. (Regular use of firewood for boiling the water for household daily consumption is a threat to our environment.)
  • It was discovered that an average of 5.51 kilograms of firewood is consumed by any ordinary household for boiling of water twice a day or about 2, 011.15 kilograms or approximately 2.01 tons annually. If the CO2 production standard for 1-kilogram of firewood is 1.83kg, then this would translate to 3, 680.40 kilogram or 3.7 tons of CO2 emitted in the atmosphere by a household annually. The annual carbon dioxide emitted is equivalent to Php15, 494.50 or US$368.92 per household.
  • Reducing/eliminating the use of firewood for boiling water decreases the threat of CO2 to our atmosphere.

Economic Benefits

  • The cost of time saved from boiling of water for household consumption for a year is at Php3, 331.84, the annual cost of fuel saved at Php8, 466.94 and the cost of time saved from either buying or collecting firewood at Php10, 516.00.
  • The annual total economic benefits of poor household who uses BSF as an intervention to access safe drinking water is at Php34, 226.78 or US$814.92.00 with benefit-cost ratio at 12.48 .
  • The economic cost-benefit of the household is at Php31, 484.04 or US$749.62.
  • The Biosand Water Filter could assist the economic needs of the poor household from avoiding illness that will cost their productivity and save at least 12.48 times that of the cost of the filter.
  • BSF provides 21.80 times more benefits than its cost, for a minimum of 20-years. Hence, the minimum household savings per day with the use of BSF is at Php156.33 or US$3.72. Furthermore, 20-years of proper use of BSF, household minimum savings is at Php1.141Million or US$27, 171.71 from its benefits.

Water Quality Benefits

  • 80.15% of the respondent-users attested that water from the BSF have not provided problems in the household level.
  • The recipients said that the water taste like bottled-water or mineral water.
  • The rate of flow of the water between 600ml to 800ml per minute is satisfactory by 49.62% of the users.
  • 91.60% claim that they have not been affected with waterborne diseases. They trust the treatment capacity of the water filter. After one year of usage, the filter is still effective in removing pathogens present on their drinking water.

Poverty Alleviation Benefits.

BSF has three identified ways that could contribute to poverty alleviation among poor household in the Philippines.

1. Household economy. With BSF, properly utilized according to standards, would tend household to save at least 12.48 times that of the cost of the filter annually or a daily savings of Php156.33 or US$3.72 for 20-years.

2. Health. Water health of household members is improved from both waterborne illnesses and indoor air pollution cause by smokes from fuel wood. The annual cost of improved health individual household member is at Php10, 082.06 or US$240.05.

3. Environment. Savings from environmental degradation due to carbon dioxide emission is at Php15, 494.50 or US$368.92.

The Biosand Water Filter Details

Width: 30.5cm x 30.5cm (12″x12″)
Height: 91.5cm (36″)
Concrete Filter Weight: 75kg (165lbs)
Aggregates Weight: 75kg (165lbs)
Total Weight (no water): 150kg (330lbs)
Total Weight (with water): 170kg (375lbs)