Statistics show that one billion people lack safe drinking water. Every day they risk their lives and health by drinking from contaminated water. While staying at Crossing Cambodia, I got to help Water For Life build a biosand water filter. It was such an incredible opportunity to help them build something out of simple material that can be purchased around the world. The total cost of the materials was under $12 and will give them clean water to drink and use!
We MacGyvered the filter by painting a cement pole with more cement to make it water tight. Then we added a cement layer to the bottom. We chiseled a whole on the side so that a pipe could fit snuggly for a spout. The next day we patched the bottom and spout area with more cement and added connecting PVC piping to the spout. The filter just needed sand and it was ready to go! Sounds too simple to be true, right?
Here’s how Biosandfilter.org explains how biosand filter works:
A slow sand filter contains biological activity and is therefore often referred to as a bio-sand filter. As micro-organisms such as bacteria, viruses and parasites travel through the sand, they collide with and adsorb onto sand particles. The organisms and particles collect in the greatest density in the top layers of the sand, gradually forming a biological zone. The biological zone is not really a distinct and cohesive layer, but rather a dense population that gradually develops within the top layer of the sand. The population of micro-organisms is part of an active food chain that consumes pathogens (disease-causing organisms) as they are trapped in and on the sand surface. The uppermost 1-3cm of this biological zone is sometimes referred to as ‘schmutzdecke‘ or ‘filter cake’. Which is defined as a layer of particles deposited on top of the filter bed or biological growth on top of the filter bed.
I am so thankful to Water For Life for coming out and taking the time to teach us how to make these filters!!
