Impact Areas

A community dialogue facilitated by a CHILD official on the state of water and how a BioSand filter works to purify water up to 95-99% purity.
A community dialogue facilitated by a CHILD official on the state of water and how a BioSand filter works to purify water up to 95-99% purity.

CHILD has four impact areas which include health, education, economic development and environment conservation.

1. Water Sanitation & Hygiene (WASH)

CHILD is actively engaged in community sensitization about the health dangers associated with consuming contaminated water. Community meetings are vital and while we appreciate the central role played by women in managing water resources, our meetings are attended by men as well. CHILD has established that access to clean and safe water is still a challenge to several communities in Nakaseke as a sizeable population still uses and consumes dirty and contaminated water. The local communities have been sensitized to understand the linkage between illnesses associated with drinking contaminated water.

CHILD’s water sanitation and hygiene interventions have seen it conduct assessments of the state of affairs in school and the findings have indicated that  nearly all schools have huge gaps in delivery safe water and adequate sanitation facilities to the pupils.

Girls are adversely affected by lack of water and sanitation facilities. This mainly affects girls that have reached puberty and need sufficient amounts of water and facilities that ensure privacy when they are in the menstruation. This poor state of affairs adds to the depressing global statistics on the poor sanitation trends in especially the developing world.

Two men by water.
A community member and a CHILD official by a water source

8/10 schools in Nakaseke do not have safe and clean water within the confines of the school compound. The available option is for the pupils to get water from dirty and contaminated water sources and this has made a sizeable number of children vulnerable to waterborne diseases.


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 biosand filter is smaller (about 3 feet tall and 1 foot wide) and adapted for intermittent use, making it suitable for use in people’s homes. The filter container is made of concrete and is filled with layers of specially selected and prepared sand and gravel. The sand layer removes pathogens and suspended solids from contaminated drinking water.

It is a simple technology developed by Dr. David Manz in the 1990s at the University of Calgary, Canada. It is a small household unit that is capable of removing up to 97% of the bacteria and 100% of the parasites found in contaminated water.

No replaceable parts.. Very little maintenance required.

It will also remove many of the dissolved metals and other compounds that can cause a foul odor and taste. The filter can treat any source of non-chlorinated freshwater, including wells, springs, rivers, ponds, and rain.

In short, the BioSand Water Filter will make your water smell better, look better, and taste better. More importantly, the filter will remove the harmful bacteria from your water that leads to diarrhea, dehydration, joint pain, liver problems, and a host of other health complications.

The BioSand Water Filter has been tested repeatedly for more than 15 years. These tests have proven that the filter is capable of removing:

  • More than 98% of E. coli bacteria
  • More than 97% of fecal coli-form bacteria
  • 100% of protozoa and helminthes
  • Up to 90% of organic and inorganic toxicants
  • Greater than 75% of iron and manganese
  • HOW DOES IT WORK?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 Bio-sand 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. This procedure, sometimes called the “swirl and dump”, should only be performed when the filter has slowed considerably. The need for this procedure will depend on the amount and quality of the raw water being put through the filter. If the water is relatively clean, the filter can likely run for several months without requiring this procedure.