BIO-SAND WATER FILTERS:
A bio-sand water filter is a simple technology which is well suited for developing countries where other clean water systems are not available. These systems cost approximately $20 per person served.
The Bio-sand filter is a container that holds sand and gravel to produce clean drinking water naturally. It is constructed of locally available materials (sand, gravel). These systems are great because they do not require electricity to work, and they do not have expensive parts to be replaced. Maintenance is simple and can be done by the bio-sand filter owner. It's so simple everyone in the household can use it.
The bio-sand filter treats polluted water with a biological layer covering the top layer of the sand bed. The "good microbes" in the bio-layer feeds off of the "bad organisms / microbes" and develop an active organic community. Organisms like worms and protozoa can't pass through the sand bed so there is a natural "die off" process that happens too. The biosand water filter can effectively filter out up to 99% of all waterborne diseases caused by bacteria, protozoa, viruses and worms, giving local families an affordable solution for their clean water needs.
A typical bio-sand filter can produce about 6 gallons or 23 liters every hour and provide enough water to meet the needs of 10 people or 3 or 4 families.