I would like to start a permaculture farm in the native village of my father which is around 40km from Bamako, the capital of Mali Western Africa.
At the moment there is no drilling well, only a small well with very questionable water : Each time I've drunk some my tummy has felt it. Some time you end up with frogs or instects of all sorts in your water.
I plan to settle down there next year, but wonder what would be the easiest way for me to purify the water for drinking uses. Indeed, for a few months I might not have a drilling well so I need to find a way tu purify some of the current well water.
Of course this being a isolated village, there is almost no electricty so is there any low tech possibilities for me to clean the well water ?
I heard Clay was efficient in cleaning well water, but finding enough clay for a day to day use, might not be so easy.
Any other ideas ?
I think the real way to purify your water is something like the following: Find yourself stones, preferably of different sizes. Lots of them. Either sort them by hand or make a rudimentary seive of sorts to help separate the big from the medium and the small. You also will need to find some clean sand, also of different grades if you can, coarse to fine. Finally, you need a perforated pipe or tube capable of keeping an air channel under ground while letting water through. If this isn't available, in a large enough hole, you could make an inner well wall designed to let water trickle through, but this would be more difficult.
Before you actually execute this plan, make sure you talk with people in your area who might have seen this kind of thing for problems they'd encountered specific to your area and climate. I'm sure anyone with more experience than me will note any problems with my plan and suggest safer alternatives or tweaks, so keep in mind that I am making these suggestions without knowing the variables specific to your situation.
You want to make a gravel and sand filter for your well. Dig it out as well as you can, preferably until you've found some kind of natural bottom, a clay layer or bedrock, but you need some depth. The idea is to wrap your pipe or tube in something like a cloth barrier to keep fine particles out. Then you begin backfilling your well from the outside in, making sure the fill with the largest particles is to the outside, getting smaller as they approach the particle barrier. Incidentally, if you can get or make lots of charcoal (biochar), you could add this as the layer between tiny pebble fill and coarse sand, and it would act to trap and filter out extremely small contaminants. Your fine sand layer would be the last one, unless you have clay that you can powder and add, but I would be concerned with free clay particles, or with them swelling and sealing out the water you want to pass through your layers into your new tube well.
This idea is a lot quicker and easier if you have some salvaged materials to reuse, and has to be tailored to the environment, but the idea of a sand filter is time tested.
It just occurred to me that you could, depending on materials, leave your current watersource as it is and build a filter using the same principles and pour water through it, but I could see such a setup needing two or three drums of any size, but 55 gallon ones would be best for lots of water, and you'd need to fill a top reservoir to let gravity pull it through a filter of some sort (probably stones, pebbles, biochar preferably, two or three grades of sand if possible, and your filter cloth), but once you were to build that, all you'd have to do is keep filling it, and gravity would keep pulling the water through.
I would love to know what ways, other than drilled wells, people in your area traditionally used to purify their water. I would be surprised if there weren't clever solutions there.
Good luck, and please keep us posted!
Thank you so much for the amazing post.
I like the idea of setup with two or three drums.
I think I'll try it this way. Short term wise it should be enough.
You're right though, I should also ask for the traditional way people have been purifying water in the area. I'll let you know when I know more :p
Thank you once again
Check out artificial wetlands and constructed wetlands, on Google Images. I'm sure that a miniature version as little as 2 meters long, would go a long way as the beginning stage of water purification. Rice, water chestnuts, lotus or other edible plants that don't mind being waterlogged, would turn your purification system into a garden.
Though I wouldn't call creating an artificial wet land quick and easy, I think that it would be good complement to any permacultural setup after the immediate needs of hydration are met, especially with an adjacent orchard or other perennial-centric garden. That's the kind of thing that kicks off different microclimates where there once was no variation.
For what it's worth, I differ with Chris's design above (and the first few sand filters made were more or less like what he describes). It's basically the reverse of how you want to do it: big rocks or urbanite for the bottom layer where the perforated pipe (and no cloth) resides, then smaller rocks above that, then coarse sand, and finally fine sand. Doing it this way sets up the biofilm in the upper layer of the sand and when it's established it can trap really small stuff, all the way down to some viruses. Leaving out cloth barriers also removes a likely early point of failure. The first sand filter I constructed had geotextile separating the various grades of material, and the stuff blocked up within two weeks.
I have friends in Kenya who only consume water that has been through a commercial filter, because of the risk of Cholera. Those who can't afford it, drink tap water. All of the systems described, would greatly reduce pathogens, if not eliminate them. People whose families have lived in those areas for a long time, may experience no difficulty from low-level contamination. Most of us in the west, drinking the same water, would get a horrible case of diarrhea and the dehydration that comes with that. For long term treatment, something like what I have described, followed by filtration similar to what Chris described in his first post, would surely make the water safer.
So would a shallow seep into dark pebbles into the sand filter before the barrel act as a UV pathogen killer?
I have an engineer friend who took a course to go work for Doctors Without Borders (Médecins Sans Frontières). He gave me his text: Engineering in Emergencies to brainstorm my own potential water intake on my creek.
For what it's worth, I differ with Chris's design above (and the first few sand filters made were more or less like what he describes). It's basically the reverse of how you want to do it: big rocks or urbanite for the bottom layer where the perforated pipe (and no cloth) resides, then smaller rocks above that, then coarse sand, and finally fine sand.
This is pretty accurate to Phil's credit. The larger rocks are near your outlet pipe. The method that Chris K described originally is a possible solution, but is more prone to being clogged by bacterial agents or clays/silts, as is using any type of cloth near the pipe. A person can also put some larger round rocks near and on the surface of the finer material to good effect in aiding water penetration from the surface. Many alternating layers of charcoal and sand (in the fines area) are highly effective at screening bacteria, and fine particulate. The less standing water the less chance of harmful microbes getting involved. If you are going to have standing water, then you want diverse habitat/species to allow a rich system of aerobic biology to flourish.
I'll give my permacultural perspective at the same time as adding some stuff from this text.
The engineering text does not go into swamp (aquatic plant centered) systems of filtering... but from what I have read of gray water treatment, the more (non toxic)aquatic or semi aquatic plants you have in the upper portion, the more biological filtration, and the more shade. With shade, you get cooler water, which has less bacteria. Planting trees uphill of your spring, and on the sunward side are very helpful in increasing natural water pumping and shading the site respectively. You have to make a judgement call on the amount of plants, though, in the water itself, in relation to the amount of water flowing from your source at it's minimum flow times. Sometimes the volume of plants will be too high for the amount of water, thus drinking all (or too much) of what is there. Reforestation of the area upslope is the best way to charge the underground zone that is feeding your spring, while swales and upslope pits are secondary to but possibly in concert with the planting of trees.
Your goal is to have water flowing, continuously, out of your spring, in as clean a state as possible. If you have gravity as your ally then use it to create oxygenating water falls into gravel catchments, shading the splash zones from evaporation, and/or create flow forms that oxygenate via reversing flow directions in each consecutive downhill mini pool.
In the book they show the best way to create a cheap outlet pipe (as perforated pipe is not often available in emergency zones, but regular straight up pipe is almost always somewhere around). Take any thick walled pipe, and cut it transversely (not longitudinally) with a hacksaw. Longitudinal (lengthways) cuts can cause the pipe's slots to collapse under compressive forces, particularly with thinner walled pipes.
A regular hacksaw creates slots around 1mm.
Slots can be cut into three 'sides' of a pipe, separated into thirds on the circumference. It is recommended that slots from each of the three have a minimum of 20mm's of solid pipe in between. Down the length of the pipe, an image in the book shows a pipe with 11 slots hacksawed across the pipe in a space of 300 mm, with a (stabilizing) gap of 40mm between that and the next 300mm section of slots, then the pipe would be rotated 1/3rd and leaving a 20mm stabilizing spine, cut again into the surface with a series of 11 slots in 300mm's. It looks like a three inch pipe in the drawing, which shows a cross section with three slotted sections cut in with three 20mm solid spines.
It is stated clearly that a longer pipe is much more effective at increasing water flow, than using a wider diameter pipe.
Of rocks, round rocks allow more water flow than angular rocks (which, by nature, lock their flat surfaces together/creating a potential seal), and so round rocks are what you want near your pipe. You want flow, but you want a filter. So you have layers of fine material (such as sand and charcoal) at the surface of your system with round rocks increasing in size toward your drain pipe. The biological filter is in your top layers. The water flows into your top layers and is first cleaned by the biology (which will improve as your system develops), as well as the physical barrier of the sands and char. It might be wise to inoculate your char with beneficial microbes which will help to inoculate the entire surface system so that it deals with any harmful bacteria, and other macro beings as effectively as possible.
Whatever the case, you want your system to flow and, if stopped at a tap, the tap not be contaminated. Good signs (with graphics instead of words), and/or appropriate education, are imperative to keeping your water source, and tap, clean. Clean hands, are important here. A hand washing program will go a huge way to preventing the spread of disease, and the establishment of a stable water gathering location/tap.
The system can be doubled, so that you are dumping water from one swamp filter into a second one, thus creating a much higher chance of eliminating the harmful biological agents.
As mentioned, any type of fence to keep domestic animals (or people) out of the spring source area is a huge gain.
It still may be necessary to purify the water, especially at the beginning stages of your system. The use of bright sunlight in clear glass is the best solution, and should be used for drinking purposes, at least until the water has been tested as pure. Again some graphic signs would be appropriate to encourage sun purifying in the appropriate way.
One of the other super important things to go along with this, is a proper system of dealing with human waste; and again, proper hand sanitation in that system. The combination of a clean water system and a clean human waste system will have massive gains for the health of the village in question.
I will read more of this book and get back to this thread if I can glean more info that I think is pertinent.
Good luck with your very noble project! Please post of your system on this thread.
This is just a very small scale purification project of a small drum, or jar with the charcoal and sand filters, adn a little tap so it can be drawn off cleanly. We are talking of using an existing well, you throw a bucket down and collect your 20L a day and don't forget to keep the containers clean too, nothing complicated. then you put the filtered water in a nice big earthenware pot in the corner of the kitchen that allows the water to evaporate and it cools a little too, enjoy!
I would not advise putting charcoal around your well pipe as it would likely break down into dirt. If you are going to do that, do it at the surface.
Also you can do a shallow well with a driven well screen. I live in an area where the ground water is pretty shallow and people are able to get clean enough water, at less than 4 meters.
The issue with bugs and frogs is probably because the well isn't sealed. I dug an 8 meter well and forgot to seal because I had to go work on something else and it got filled with frogs and rodents when the weather changed... Cleaning that out was wonderful...
If you are looking for quick, drive what is called a point well head. You need to have a high water table for this. Digging a drilled well by hand with a hand auger is doable, it only took me a week of evenings, so about 24-30 hours for an 8 meter well. Get a clam shelled auger that will accept extra pipe for extension.
Certainly the filtration devices mentioned above will strain out the visible contaminants, but you can't see bacterial/viral/chemical pollutants. The Lifesaver (registered trademark) knocks out 2 of those 3 items for sure. And as my tap water gets tested regularly,, I take it up a notch. I often think it is a far better choice than importing water at a horrendous price in plastic pollution or in human labour to produce wells of uncertain drinking value. Of course, water has to be available to be filtered.
These links you might find usefull. In its most basic form, you just need clear plastic bottles to produce good drinking water. But it's probably safer in the long run to provide everybody nearby with clean water. If nobody near you has a waterborne disease they can not infect you or the water nearby. Remember Certain minerals may cause diarrea if present in drinking water. Others are toxic in the long term - arsenic f.e. There is lots of info on this on the net. If brick, sand, clay and charcoal are available you can get most contaminants out of your water.
If available a solar cooker is a fast way to kill pathogens in groundwater.
An interesting system was developed in Venice Italy - see the links at the bottom below. They are more sofisticated but if you combine this with uv desinfection, you should have a safe system that takes little maintenance and little or no electricity.
Dale Hodgins wrote:I doubt that there would be much UV pathogen killing going on. But, almost everyone can come up with a big glass jar. After the water runs through filtration and is gathered, I wonder if it could simply be bottled and placed in the Sun for a day or two. This might require the acquisition of a few jars. Sunlight is a great sterilizer , and that part of the world has no shortage. The water would also undergo a very large temperature swing, during those couple days of sterilization.
Glass is less effective than PET plastic bottles (often readily available free). Some glass blocks very nearly all UV light.
This is where I bought it in Nicaragua: https://www.filtronnica.com/english/
And some general information: https://en.wikipedia.org/wiki/Ceramic_water_filter
It is cheap (mine costed about 20$) and low maintenance, just clean it once a month.
I know it exists in several countries, and definitely you will find it in Africa. Hopefully in Mali too.
They can even be gravity powered (poor dirty water in container on top, clean water comes out the bottom.)
Slow sand filters, etc. will work, but they usually takes a few weeks before biofilter progresses to the point where they start producing clean water. Plus they are finicky. You have to continuously flow water through them or the biofilter dies and then it takes weeks to grow back again.
I currently use both methods but not together. One location has a home made slow sand filter with activated carbon final filter. Removes chlorine & sediment. Water tastes & looks much better. The other location starts with relatively pure spring water in the mountain wilderness. I accept a small amount of sediment there but use SoDis for safety. Giardia & cryptosporidia are not fun. A sand filter will be added soon.
Sawyer Squeeze or mini squeeze. Small. Cheap. Very good filtration. Almost indestructible except by freezing. Thousands of more people would have survived Hurricane Katrina if they had one available. Sawyer snake bite kit is awesome too. Probably not easily available in a remote African village.
I have used all 3 water filtration/purification methods with undrinkable water & all worked well. No intention of fully testing the snake bite kit.
Appropedia link for Biosand filter (lighter introductory article)
Appropedia link for slow sand filtration (heavier article)