Biosand Filters

I also spent a week with the Household Water Program (HWP) team. The HWP is broken down into 2 different programs: biosand filters and community water projects (boreholes, shallow wells, deep wells). I focused on the biosand filters.

What is a biosand filter? It’s a big concrete mold that’s filled with gravel, course sand and fine sand. The dirty water is poured into the top of the filter and gravity pulls it through the sand to clean the water. The small parasites that cause sickness are actually eaten by a thing called the biological layer. It’s created from the dirty water and is a natural way for the bad things to go away (very technical verbiage). The bio filter is a few inches thick and looks like brown slime. Though it looks bad, it actually plays a very vital role in the filtration process. The clean water is pushed up the pipe and out the spout into a container where it can be drank or used for cooking or washing.

I went to three different construction sites, helped build the filters, sat in on training workshops and visited homes for follow ups. Here’s how they are built.
Filters made from the previous day are removed from their molds. Molds are put back together and greased down (cooking oil). Plumbing is added. Concrete is mixed (after sand is sifted, stones are sifted and concrete is added, water obtained from the local (but not really local) water source). Concrete is poured into mold. Large rubber mallets are used to bang the mold, settling the concrete and removing any air bubbles. Molds set for 24 hours but cure for 7 full days. Excess concrete is used to construct lids.

Sand is washed so that it’s clean from dirt and silt. How can you tell when sand is clean? I have no real idea but the local experts do. The cleanness of the sand helps determine the flow rate of the filter. Too slow of a flow and recipients won’t really use the filter because it’s too slow. Too fast and the water isn’t as clean as it should be. Clean sand is then dried and saved for instillation. Gravel is also cleaned and dried. A filter that is working properly should produce 5-700 milliliters per minute. Before all of this happens, SP has a community meeting and people sign up to help work on the filters. Each community member needs to wash sand and spend a morning helping construct the filter. They sign up for work days so to speak. Each day has 5 community members signed up (one per filter). Women also join in and wash sand or sift the materials.

Side note: I’ve seen a biosand filter project in Brazil and recipients had to purchase the filter for a significantly subsidized price. This helped ensure the owner valued the filter and cared for it properly. This wouldn’t really work in this context because people don’t have a lot of money but they do have time and energy to spend building a filter. End side note.

Lastly, filters are numbered and taken to homes by the recipients. They are then installed by an instillation technician who makes sure they are level and that the sand and gravel is properly installed. Again, the beneficiary receives training on how to maintain and use the filter. A small GPS unit is used to log the coordinates of the house so it can be easily located by follow-up staff.

This year SP in Kamwenge should make about 2,000 filters and next year hopes to hit the 3,000 marks. After seeing the way the water looks coming out of the local sources, these numbers seem like a drop in the bucket (good water analogy) but they are still significant. Funding, staffing and material resources all limit the programs expansion. It is expanding every year, but the demand for clean water in this region of Uganda is hard to keep up with.

In addition to working with the filters, I joined some SP staff for a child hygiene fair at a local public school. It was a fun, “field day” with games and skits that taught the kids about proper hygiene. My personal favorite was called “poop toss.” I taught kids the importance of accuracy when using latrines. It was basically a bean bag toss with the bean bags being the poo and the wooden cutout being the mock latrine. Students had to throw the “poop” into the latrine. The kids actually really liked it. The second game was a big relay race that taught kids when they needed to wash their hands. The latrine, cooking/kitchen and handling animals were all relay station points. The last station gave kids the opportunity to learn how to properly wash their hands. I think the kids did have fun and I hope they learned a little bit. They got a few sweets at the end for participating.

One thing that struck me about this particular week is the various backgrounds from the staff members. Most are married and with children but few live anywhere near their families. NGO jobs are tough to get but the payment is fair and the they are reliable, unlike most jobs available. They travel for the sake of the job. Nearly all of the staff I have met have worked with SP for several years but have spent much of that time away from their families. They have formed their own family environment in the workplace which is nice to see but I wish there was a better way. Also many of the field staff who work at the filter construction sites live literally at the construction site. The sites move every 4-6 months or so, as the construction finishes, the whole work site moves to the next village/ perish/town. This also means that the staff must shift with the work.

Despite the obstacles faced, the household water program is helping thousands and contributing to our lovely Millennium Development Goals, one filter at a time.