Technology We Use

Biosand Filter is the technology we use. click the link from CAWST to learn more about the biosand filter technology. Learn more

We trains locals to build, test, and install biosand filters in their communities. Many people living in regions of the world effected by the water crisis have water, it just isn’t safe to drink. Biosand filters can be constructed with locally available materials such as sand and gravel and require no electricity or chemicals to operate. Where we work

How the Biosand Works

All water containing beneficial bacteria (probiotics) along with harmful organisms. The beneficial bacteria accumulate and thrive in the upper layers of sand to form a bio-layer. When you pour water through the filter, the bacteria in the bio-layer kill the harmful bacteria in the water and purify the water as it moves through the filter.

A biosand filter will purify 20,000 litres of water per year, 3 tonnes of greenhouse gas emissions would be necessary to boil a portion of this water to make it safe to drink. On average, 3 families can share a biosand filter.

How It's Made

Locals are taught how to construct biosand filters using training courses and teaching material made available by CAWST. The construction of a biosand filter involves a four step process:

Collect and Sieve the Sand and Gravel

The technology we use contain Crushed rock which is the best sand and gravel to use and can be obtained from gravel pits or quarries. If crushed rock is not available, the next choice is sand from a sand quarry or pit. The sand and gravel from the side banks of a river can be used, but this usually requires more work and time to make it clean. Various sized sieves are used to sort the gravel and sand that will be used in the concrete to build the container and used inside the filter as filtration sand. The sand and gravel is washed once it’s sieved and sorted.