Water: Part 4 of 5 – One HWTS Model – the Biosand Filter (Warning: long post)

One type of household water treatment product that I’ve encountered here is the Biosand Filter (BSF). It was developed by Dr. David Manz of the University of Calgary nearly 20 years ago, and it is the primary technology promoted by the Center for Affordable Water and Sanitation Technology (CAWST, http://www.cawst.org). It is a modified slow-sand filter, which means it has two mechanisms to treat the water. The first is a layer of micro-organisms that live in 2 inches of stagnant water right above the surface of the sand. These micro-organisms prey on the micro-organisms that are in each batch of untreated water that is poured into the top. The second mechanism is the sand itself – the grains of sand are small enough to trap many of the remaining micro-organisms, and deplete them of the oxygen they need to stay alive since the layer is so densely packed. Water passes through the layers of sand and comes out a spout (see the diagram below; courtesy CAWST). The BSF is not perfect, and its designers do not guarantee that the water coming out the “clean” end is completely pathogen-free. Instead, they claim that it can remove 97% of bacteria and about 90% of viruses. It can not remove chemicals (but there is not a high degree of chemical pollution in rural areas like Mityana).

Fred (the aforementioned director of the chicken project) is a very busy guy – he’s implementing the BSFs in Mityana through the support of a local NGO called Connect Africa. Fred was trained by a retired American named Tex, who lives in Kampala, swears by the filters, constructs them in his backyard, and has one in his own home. In the last year, Fred has distributed 30 of them, free of charge, to schools (including Maranatha), health clinics, churches, and hotels (see the picture below, where Fred helped install 2 filters at the Good Shepherd home for physically handicapped, homeless, and orphaned children in Kampala). This isn’t exactly at the “household” level yet, but Fred hopes to get there soon. During installation, he teaches people about proper sanitation techniques, and he is on-call to receive any service and maintenance requests as they arise. So far, the requests have been very few. CAWST claims that some filters have been in operation in the field without any trouble for over 10 years. Fred recently completed his first follow-up survey with the users of the filter throughout Mityana and the results were overwhelmingly positive in every regard. The only complaint is that the filter can only provide 80 liters of improved water per day, according to Fred’s recommendations of use.

A couple of University of North Carolina studies (the first in Dominican Republic in 2005 and the second in Cambodia in 2007) showed that these filters reduced incidence of diarrhea (often the easiest outcome that can be tracked in regard to effectiveness of sanitation interventions) by 40%. I will issue a disclaimer that I have not evaluated the rigor of these studies, but if they are to be believed and the results applied universally (which is not a small leap of faith), that makes the BSF as effective as any other intervention, including chlorine (according to the 2002 WHO study mentioned in the last post). That may surprise some people, but assuming we take the leap of faith, I think it can be attributed to a number of factors. Here are a few:

• Because the water is treated at the point of use, it reduces the risk of contamination during transport.

• Even if a purification technology is lab-tested as more effective, it does not guarantee that it is more effective in its field implementation. The easier a technology is to use, the more likely it will be implemented as it is intended to be, and the BSF is about as easy as you can get. You pour water in the top, and it pushes out water that has passed through the sand layers. There’s almost no waiting, no moving parts, no energy required, and nothing for the user to do but make sure they have a clean container for the improved water (Fred trains people on this, as well).

• Even though the BSF does not filter out every pathogen, it requires no additional operating costs, so people use it every time they drink water. In contrast, household chlorination use can be intermittent depending on the variability a household’s disposable income (sometimes a head of household will forego purchasing a chlorine tablet when they are short on cash)

• There are other reasons to use the filter besides health benefits – after filtering, the water tastes better, has less sedimentation, and it cools as it passes through the sand. No other technology has these three quality improvements, and at least in Mityana, this was often stated as one of the finest attributes of the filter.

I don’t think this last point can be stressed enough. People in Mityana are not necessarily educated about health and disease, and even after education, sometimes all that information can seem removed from their normal daily activities. People may not internalize the fact that they have had less disease or illness unless they are asked about it, and may not attribute a reduction in any disease or illness to anything in particular. Others might think they don’t have the resources to implement appropriate sanitation in their home. Aesthetic benefits like the ones described above provide an instant rationale for using the BSF above and beyond the less immediate or less-easily associated health benefits. Boiled water takes a long time to cool down, and even then, it’s not really all that cool.

The BSFs are currently being rolled out in two ways across many countries. First, through a subsidized NGO approach, where the filters are provided for free like Fred has done. Second, through a micro-enterprise model where local people construct the filters themselves (the filters can be constructed entirely of locally-available materials) and sell them and provide related services in their communities.

I’m no public health specialist, so someone please drill me if I’m out of line. I’m of the opinion that the best intervention is one that works within people’s own rationale to move a step in the right (read: healthy, economically beneficial, socially beneficial) direction. I think we all need to be wary of the “something is better than nothing” mentality, because sometimes it’s not. But I think in this case, the BSF is better than nothing, especially if it means people will be introduced to sanitation and hygiene methods for the first time. What do you think? I’m happy to have someone argue with me on this one.

Of course, the best thing that people can do is use the BSF in combination with a disinfectant such as chlorine. But isn’t this a good place to start? Below is a picture of the filtered water from Tex’s house – it looked beautiful and tasted great.

Water: Part 3 of 5 – Treatment and Sanitation

Drinking water is a big problem in Mityana, as it is in most of sub-Saharan Africa. Sub-Saharan Africa is the worst-performing region in the world in this respect, and this is most true in rural areas. The UN estimates that only 1 in 4 rural sub-Saharan Africans has access to clean water. While SE Asia has made many strides to improve water quality in the past 20 years, Africa has made very little progress. The stats on Uganda, in particular, are better than Africa as a whole, but not by much. According to the previously pictured District Community Development Officer, about 44% of the population in the area surrounding Mityana has access to safe water, though I’m not sure how he’s defined it.

The piped water that is now available in Mityana is certainly not potable. But, people often drink it straight from the tap anyway. Most, though, still do not have access to piped water and need to continue fetching it from streams that are exposed to contamination of a variety of sorts. Even after collecting from these streams, some do not boil their water before drinking it. The result is often diarrhea or worse. I have spent time in the last few weeks researching the current flavor of development in this area, and it seems that almost across the board, it is extremely difficult to implement centralized water treatment systems in sub-Saharan Africa. The reasons range from broad corruption to mismanagement to inadequate funding to lack of power to lack of technical training and the list goes on. It makes me appreciate living in the United States – there’s a lot I take for granted.

In reading through the literature from the World Health Organization and UNICEF, the numbers of sick and dying people due to water problems are staggering. Estimates are that at any given time, at least 50% of the hospital beds in the less-developed world are being occupied as a direct result of poor water access, cleanliness, and sanitation (some say it’s 80%). A large proportion of the under-5 child mortality can be attributed to poor sanitation and water quality, and could be prevented. Of course, the next question is always, “at what cost?”

Because of the challenge in implementing large-scale, centralized water treatment systems, the WHO and the UN have both recently shifted to promoting “Household Water Treatment and Safe Storage” (HWTS; see, for example, http://www.who.int/household_water/en/index.html). These systems have often been found to be more effective than central systems because of the risks of recontamination during transport and at the point of use. HWTS has the advantage of educating the end-user of appropriate treatment and storage methods as the systems are installed. According to a recent WHO cost-effectiveness study (available at http://www.who.int/water_sanitation_health/economic/prevent_diarrhoea.pdf), HWTS is roughly twice as effective at preventing diarrhea as are source-based interventions, but the costs are usually much higher on a per-person basis. Of all the methods studied for treatment, household chlorination had the best cost-effectiveness ratio, and household filtration had the best overall effect (a 63% reduction in diarrhea cases), albeit at a higher average cost of prevention. The next post will be about one HWTS system I’ve encountered since being here.

Here is another account of the water situation in Uganda, and here is one more.

Water: Part 2 of 5 – Improving Access

Roughly 10 years ago, the Mityana Town Council instituted a project to drill boreholes for public water access in the town (just like the well pictured in the last post). These wells caused a great stir, and according to Patrick, people would line up as early as 2 a.m. for the privilege of being first in line for the upcoming day’s water. However, if you did not get to the well by 6 a.m., the line could often be so long that it took longer to wait at the well than to go fetch water the old way – at the nearest stream. Shortly after installation, the well broke. According to Patrick, because the well was in a public place, it was constantly played with and misused by small children.

Luckily, the Town Council had prepared for this – they had trained people to repair and maintain the well. But after 4 years, the repairs became so frequent that the well fell out of favor in the community, the repairers became frustrated, and the well became inoperable. In town there is still a shop with a sign indicating they provide well repair services, but Patrick told me it closed down 6 years ago. I attended a recent presentation by the District Community Development Officer (pictured above), and he said that less than 40% of the borehole wells in the district are operable. (In contrast, Patrick had a private borehole drilled for Maranatha’s primary school in Nkonya over a year ago. The well has been operating without any trouble. He believes it is because Maranatha owns it – since it is private property, it is carefully protected.)

The good news is, the failure of Mityana’s borehole in part led the Town Council to consider additional options for providing water access to its residents, and they decided to develop the infrastructure for piped water. So in March of this year, Patrick, his family, and the Maranatha Schools were the first in Mityana to receive piped water and a septic system. Of course, it cost quite a bit for Patrick and Maranatha, but it was an easy decision to make. Patrick is now one of a handful of Mityana residents with a flushing toilet, and the new dormitory being built will have the finest bathroom facilities of any boarding school for miles and miles around.

Water: Part 1 of 5 – The Current Situation in Kigalama

Pictured here is an example of the current water situation in rural Uganda. It is very common for boys and girls leave their homes 2 hours before sunrise to go fetch water from nearby streams using these 20-liter “Jerricans”. This ensures they will be back in time to get to school in the morning. As the picture indicates, often children will need to go back at mid-day to go fetch more.

This picture is probably close to what you have in your head when you think of water in rural Uganda, and for the most part, it’s the situation you would find. In this case, the water is a little closer than it would otherwise be because the source is a borehole well and not a stream or lake. As dry season continues (it started in early June), water becomes more and more difficult to find unless there is access to a well like this one.

Maranatha’s Kigalama (pronounced Chee-ga-la-’ma) Primary School, roughly 15 kilometers from Maranatha’s central school in Mityana, uses this well as its main water source. It is over 1 km away from the school, and to get enough water for all the 260 students, they hire a man on a bicycle who gets paid 500 shillings (roughly 30 cents) for each Jerrican of water he brings to the school. He can put 4 Jerricans on the back of his bike for each jaunt down to the well. In total, he brings the school 14 Jerricans a day (I’m not sure why this is not a multiple of 4; Maranatha is willing to pay for up to 30 Jerricans a day). So, he makes 7,000 shillings (the equivalent of about $4.50), which is considered a decent living in his community, where people are mostly surviving on subsistence agriculture. Meanwhile, the students, teachers, and staff receive a grand total of 280 liters of water. That’s about 1 liter per person per day for cooking, cleaning, handwashing, and drinking. Of course, the water is boiled to make it suitable for drinking.