Water for Cambodia (WFC) staff have interviewed and chosen the recipients of the 268 water filters in the three villages… Char, Romeat and Kandal. Approximately 80% of the villagers will receive filters this year.
Our filters are under construction and being stored at WFC. Delivery will be in May, June and July 2018.
Before we look at pictures of families with new sand filters, let me share with you some information on Biosand filters and how they function.
Our Biosand Filters (BSF)
Since 2006 Water for Cambodia has been building and installing Biosand water filters in rural villages of Cambodia. These filters are household units that produce clean water directly from contaminated sources. Polluted water is poured in the top, filtered through the sand and gravel layers and within minutes clean drinking water pours from the spout. Filtered water looks and tastes good, an advantage over well water where high iron content has an offensive taste and color. One filter can produce enough clean water for a family of 5-8 for many years.
According to a summary of laboratory and field studies for Biosand filters conducted by the Center for Affordable Water and Sanitation Technology (CAWST.org) they remove the following from contaminated water:
- up to 98.5% of bacteria
- up to 99.9% of protozoa
- up to 95% of turbidity
- 90-95% of iron
For more information on the technical aspects of the Biosand filter visit www.cawst.org.
Biosand Filter Construction
Each filter is constructed of a concrete body 3′ tall and a foot square filled with layers of gravel and sand (see schematic above). Source water is poured onto a diffuser plate at the top of the filter to prevent disturbing the top layer of sand. After passing through the sand and gravel, the now clean water travels through the copper pipe and out the spout using the force of gravity alone. There are no moving or mechanical parts to break.
The key to the effectiveness of the filter is the biological zone which naturally forms on the sand surface. This layer consumes harmful bacteria and other pathogens. As the water passes through the sand layer larger contaminants (e.g. parasites) are trapped and others (e.g. viruses, certain organic compounds) are attached to the particles of sand, a process called adsorption. In the lower layers of the filter where oxygen levels diminish organisms die a natural death.
A family receiving a biosand filter pays a nominal fee and is actively involved in the installation giving them a vested interest in maintaining them. Also, instruction in filter operation and maintenance as well as basic education in hygiene and sanitation are provided. Biosand filters in general require very little maintenance (occasional stirring up of the top few inches of sand and scooping the suspended sediment) and are still functioning effectively more than 10 years after installation. Filters are manufactured locally using local materials.
Please Note:
The Villagers have dug 19 wells and for the first time in their lives are getting non-turbid water. In our hygiene classes we explain that the fact that the water is clear doesn’t mean it is potable. We explain that washing their bodies, gardening and flushing can be done with the water directly from the well but cooking, vegetable washing, wound care, brushing teeth, drinking and washing dishes needs to be done with filtered water only.
The blue bottle seen in pictures below, is supplied by us. It is used to collect water at all times. The pictures show the bottle just sitting there because the filter is being charged with water so the biological layer can develop in the top layer of sand. It takes about two weeks for the bio layer to activate.
In the last photo you can see the system working once activation has occurred. The blue bottle has a small opening and cover to limit contamination and it has a spigot so dirty hands aren’t dipping a ladle into the water.
