Africa Water Purification

Working in the market that I do I can honestly say that if Watercone is changing $30-50 per unit and are marketing it as a "help the 3rd world" type company they are raping people. There is probably less than $2 in cost there. Add in another $2 in labor and machine time and you have $4 or less total cost. We have large injected molded plastic parts made for us and they cost very little. We Vac. Form even larger parts as well. I guess everyone has to make a buck.
I did some "research" on my recent trip to Uganda (I flew back to the states on saturday morning). The summary of my research was that, in most places in and around Kampala, a borehole, or well, is the first step. Expensive, but most effective. Second - boiling. The firm confirmation of the locals is that a well combined with boiling the water provides the safest water for them in the most simple way. No filters, no UV treatment, nothing. In one man's words: "Give my village a well, and ensure every person in the village has a metal pot, and we'll be fine. The real question is where to find work."

In short, this trip opened my eyes to the fact that sometimes, we may be over-complicating things.
I don't know how it is in Uganda, but in many places the issue with the boiling part is the lack of fuel and high rate of fire related accidents. I agree, without a well or a source of marginally clean water to begin with a well would be the natural first step.
Thanks for the great thoughts. I am close to having a solution. Some of the solutions mentioned are very good but not possible in our locations. Since we are trying to treat water for large groups (60-120) at a time some of the ideas mentioned are simply not possible.

Our first choice is always a deep well but some of the locations cannot get a drill rig to them and are located in areas where wells cannot be dug. for instance one orphanage is at the end of a dirt road that takes 3 hours from the main road to get to. Every rig we have talked to refuses to go down it.

Boiling is also a problem at some locations. Boiling water for 100 people requires a lot of wood. Since Kenya is more developed wood has to be bought or can be cut from state land only if you have a chain saw, a permit, and a truck to haul it with. Believe it or not wood is right now our biggest monthly expense. Since most of the cooking is done over a wood fire or wood stove it is amazing how much wood we use. It has proven to be surprisingly costly and problematic.

Thanks for all the good ideas and thoughts. It is good to see all of our community knowledge and experience go towards a noble cause like clean water in developing countries.

Ok for anyone who has been following this I thought I would post a follow up.

I spent two weeks in Western Kenya last month and had a very productive visit. On top of our massive medical campaign I was able to set down with local village leaders, health care workers and our orphanage directors.

As I said before our main objectives have been:

Clean water to improve the health and quality of life.
A solution that can be made, maintained and resupplied in country.
As solution that is easy to maintain.
A solution that can be easily implemented with little training.
Something that works from 60-100 people on a daily basis.

I think we have found our solution. It's easy to make, can be made from locally available products, is strong, simple, reliable, cheap, needs almost no maintenance, can be adapted for groups our size, and is almost indestructible (it's made of concrete).

It's called a Bio-Sand filter. A complete description can be found here.

A bio-sand filter is also sometimes called a "slow sand filter" and here is a great description from the site...

"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. Slow sand filters are usually cleaned by scraping of the bio-film and/or the top sand layer."

The device is about the size of a 20 gal trash can and is filled with 3 layers of sand (fine, course, and small gravel) and uses gravity to filter the water through the sand and "biological zone" (basically algae). It has been tested and is proven to remove bad bacteria, viruses, protozoa, and helminths 99% of the time. It can also be made to remove arsenic. It needs almost no maintenance other than the "skimming" mentioned in the paragraph above and will only cost between $10-15 US with NO MONEY NEEDED FOR UPKEEP!!!!

The down sides are: It does not filter chemicals like pesticides, cannot handle high turbidity for long periods of time, and it cannot remove salts or hardness of the water.

I am still learning about this and see lots of potential for it in our application. A team is leaving next week to go back and they will be testing our water supplies to get a baseline on just how "bad" the water ism but this has lots of potential.
Funny- That was my first suggestion.

Good to see you have come up with a solution. I think even a half step is better than no step at all.

Keep in mind, the parasites and protozoa are acute nasties, they are going to give people the runs and make them sick the quickest.

While not ideal, having some level of contaminants like pesticides and metals is not as bad. Most of those things are "chronic" problems.
A few interesting reads for down the road:

getting people out of the outhouse and into the classroom will for sure be a step in the right direction to develop healthy happy villages


Expedition Leader
Insanely Complicated

This is WAY beyond the technological level of anything going on in the CAR. That said, it is a VERY exciting concept if someone had an absolute ton of money for construction and training. I wouldn't worry about pesticides (there aren't many/any) or salt/hardness (the goal is to stay healthy). The goal is to kill off the cholera and guinea worm. Do the that and the rest is window dressing.

The maintenance requirements are extremely complicated, but might work very well in a disciplined environment like an orphanage. And that might be enough to do proof of concept. If it can be shown to work in the school, then the village headman might be able to impose it on the village. Certainly worth a shot.

The problem is that no one will understand the need to preserve the bio layer and it is likely to get dumped as being "dirt."
To quote from the article: "In some projects it is found that a majority of households will either forget or ignore cleaning advice. In such cases, bio-sand filters cannot be considered a 100% failsafe method of water purification despite their potential, but rather as a ‘better-than-nothing' interim method of water treatment. This highlights the need for intensive teaching methods. It is likely that better information, teaching of cleaning methods, or improved or more frequent follow-up will lead to much better results." That is always the problem wheen high tech solutions like this meet the real world. Your cabin in the woods? No problem. An African village? Not a prayer. Still, in a school/orphanage environment, this might work well assuming you could produce the volumes needed.

I will shop this around and see if there is any interest. 74% of all Central Africans have no access to safe water - one reason that the life expectancy is lower than Somalia. Indeed, mortality is so high that the CAR is approaching negative population growth.

Thank you for publishing the links.
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Jonathan Hanson

Supporting Sponsor
Early on in this thread I expressed skepticism about the easy UV purification method. It appears there is still room for doubt, or at least further study:

The problem with any system is that adherence to the protocol tends to degrade with time. If two days dwell time is called for, it's likely that will be cut short. If a certain amount of an expensive chemical is called for, the dosage will be cut to save money.

The good thing about a filtration system is that is is difficult to circumvent the procedure and reduce its efficacy.


Whatever happened to Dean Kamen's water purification system (Slingshot)? He had come up with a system that used a Sterling engine (powered by anything that would burn) to generate power and then a water filtration system that used the waste heat from the sterling engine to essentially boil "anything that looks wet", collect the vapor, and turn it into drinkable water.


Anyone know if anything ever came of it or if it was ever put to any practical use? Seems a system like that (if they managed to get it workable) would be ideal - virtually no maintenance and what little must be done can likely be trained into anyone with basic mechanics knowledge.
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Expedition Leader
Distillation works ...

but it still takes a certain number of btu's to boil water. And that takes fuel of some kind. And you still have to clean the crud out of the distillation chamber. And it is a challenge when:

-- Income is less than U.S. $1 per day
-- Education is less than five years and may, in fact, be zero.
-- Literacy is less than 50%.

Things that look real easy are real hard in the real world. People don't choose to get sick and die if they know how not to. (We'll ignore, for the moment, people living in the bush due to conflict. Take an illiterate population and add conflict and you have a real mess.)



The human portion of this equation must be nearly intractable as engineering solutions seem to abound.

Even in the developed world the biggest problem with any solution always seems to come down to the people. There are a few posts here that have been real eye-openers in terms of why things that seem so obvious to us break hard when in the hands of others. I work with computers and the single hardest thing to engineer around in the solution to any problem is the user. It would seem you have a similar problem (for different reasons) with much more dire consequences.

One of the things I read about over and over again is that non-organic (meaning not home-grown) solutions that are given to a population tend to be shortcutted and then abandonded or completely repurposed (like using the aforementioned mosquito nets for fishing) rather than maintained and used properly when not developed locally or driven by a local initiative.

Is that largely the problem here? Do you see projects succeed when pushed by local agencies or entrepreneurs that failed when outside NGOs do the same?

I also found this really cool system some guys are testing in the Sudan right now that is a ingenious and simple way to hand drill wells. It can be done with as few guys as 4. It's crazy simple and kinda encouraging for places like the C.A.R where supplies and technology are more sparse. My understanding is Kenya looks like Hong Kong compared to the C.A.R.

As I said a team leaves this Friday for Kenya and it seems we learn more about this every day. I will keep everyone posted on our progress and our findings and experiences.


Expedition Leader
Very Interesting

Just finished a meeting with North Carolina Air National Guard about water projects in the CAR. They are closely linked to UNC (which is doing work on your biosand filter) and we are going to explore various filtration devices. They are an engineering group who will be engaging with the local military engineers. If we can find a system that the engineers can install/maintain for their own use, then we might be able to propogate it into the community.

Please send info on the hand drill. Can it do 30 metres? What do you do for a pump?
What about pesticides and heavy metals?

This may not be what your looking for, but I read that in Kenya they are taking contaminated well water and putting it in clear plastic bottles. Then placing the bottles on corrugated roofs for 48 hours.

A mix of the temperature and UV kills all contaminates and makes the after safe to drink.

Cheap, easy, African solutions in comparison to high tech, expensive, complex Western solutions.
UV is good against biological threats..but what about heavy metals and pesticides?