It is the 1st (ikini) of the Enterprising Communities series to be published by ALARAN DEVELOPMENT ENTERRISES. This series aims to assist African enterpreneurs in building business enterprises based on innovations in science, technology, engineering and medicine.
HOW TO (NOT NEED TO) DIG A WATER WELL (KAANGA)
Introduction:
The next time any African introduces themselves to you as Engineer this or Engineer that, tell the wastrel to go dig a borehole for a village or fetch water with a bucket. Are you tired of fetching water with a bucket? The Enterprising Communities series shows you how to harvest rainwater...
Africa's home grown engineers are just not worth their professional title. That is what the Nigerian government thnks when it gives estimated 94pc of all engineering works to foreign consulting firms. From bridges to stadiums, from multi-storey buildings to GSM masts, from roads to wells, no local engineering firm is deemed sufficiently capable by national or state governments. These so-called engineers should redeem themselves.
There is talk of Chinese engineers building 598 water wells in eighteen Nigerian (18, meejoola) states - including Ogun, Oyo, Akwa Ibom and Abuja. Chinese Engineers digging boreholes in Nigeria?! Whatever happened to the yearly thousands of civil, mechanical, electrical, chemical B.Eng and M.Eng produced by higher institutions in these states? WATER WELLS, haba. People in the village have been building kaanga (water well) and shalanga (pit latrine) for aeons, without importing Chinese, Irish or Gabonese to provide "technical assistance".
This is a very serious matter. There is an oncoming GLOBAL shortage of clean water. In fact, scientists are predicting that future wars over water supplies will be more intense than current conflicts over crude oil supplies! Those who live in places where drinking water appears, from a centralised waterworks, wherever you open a tap will notice that their water bills are annually increasing at above-inflation rates. So everybody can benefit from knowing how to harvest water locally, cheaply, cleanly and efficiently.
Whether you live in the city or in the village, in the rain-soaked swamp or in the drought-stricken areas can still benefit from rainwater harvesting and from runoff water harvesting.
RAINWATER HARVESTING
Requirements: corrugated roofing sheets, a filter made from a 50-litre plastic keg (optional), collector pipe (plastic), distribution pipe (plastic), and water butt The water butt can be above ground tank with a tap attached to it. Alternatively it may be below ground tank with a small handpump attached to it. Above-ground butts are easier to clean while below ground butts are better supported. Below ground butt may also be dug out tank with walls, bottom and top covered with cement/concrete.
1. Build your house with a sloping (A-style) roof design.
2, Cover the roof with strips of corrugated sheets. Make sure the bottom edge of sheets near the top cover the upper edge of the next lower sheet. Let the bottommost sheet overlap the edge of the roof.
3. Collector pipe: Cut off a section from some of your pipe so that the 0-shape becomes U-shape. Put the collector pipe along the length of your roof with the roof overhang inside the bowl of the U-shape.
4. Filter/Connector keg: Turn the keg upside down. Cut a hole in the side farthest from the sprout for insertion of the collector pipe. You may fold some clothing several times and tie to the collector pipe at its insertion point. This acts as a filter to prevent debris from the roof from entry your rainwater harvesting system. (lace curtains are excellent for this purpose). Attach the keg firmly to the side of your house. Place the bottom (capped) end of the keg over the entrance of the direction pipe. Remove the cap from the keg.
5. Direction pipe: Place one end over the end of the connector keg and place the other end OVER (not into) the top of he water butt.
6. When rain falls, let the initial rainfall flow away before inserting the directon pipe into the top of the water butt. In the heavy rainfall conditions experienced across most of sub-saharan region of Africa, you may find that a family of six can more-than-satisfy their domestic water needs from rainfall collected in this manner.
7. Rainwater is relatively pure compared to groundwater. If you regularly keep your roof and the collector pipe clear of debris, you may safely use this rainwater for washing clothes, flushing, body cleaning and other non-injested usages. It is recommended that the water be heated, and allowed to for some minutes, before drinking or cooking. Boiling kills pathogens that may be too small for you to see and yet they live in the water.
8. If an underground water butt is used, take care to ensure there are no pit latrines or sewage tanks in its vicinity. If in doubt, put the water butt on the opposite end of the house from any sewage facilities.
COMMENT: Anyone who has lived with a leaking roof will bear witness to the volumes of rainwater that can efficiently be collected with this system!
RUNOFF WATER HARVESTING
Farmers need lots of water for irrigation and animal husbandry. People in drought-stricken areas may need to walk several miles to find a water hole. Many Nigerians/Africans do not have tap-borne water in their homes. In all these cases, women and children are often tasked to walk miles in search of drinking water. They regularly carry loads of 3kg (mudu meeta) on their heads two to three times a day. Yet they live in places where rain falls heavily and runs off into gullies thereby causing severe erosion and loss of topsoil. This runoff rainwater can be harvested easily in rural areas or combined with the rainwater harvesting method discussed above.
Requirements: Cement/concrete; an open space about 2000 sq metres; water pump; wire gauze
1. Clear an area of 500sg metres in a corner of your space. Inside the clearing, dig a CIRCULAR-shape underground tank of radius 5 meters. Make it as deep as you like.
2. Cover the sides and bottom with cement blocks or concrete. The bottom should be covered. This is not a well that taps underground water. You don't want the water that you collect to drain away!
3.Make an indentation near the lip of the underground tank. This indentation may be 1.5 metres wide and about 0.5 metres below-ground-level at the inlet of the tank. So, the indentation is deepest at the inlet of the tank and becomes shallower until it reaches ground level. It will look like the pouring end of a jug. Now make 5 cement/concrete mini-slopes between the tank inlet and the "pouring" end. Each slope has a vertical face that is about 0.1 metres high. This face points away trom the tank. Cover the sides of the tanks and the indentation with cement/concrete so that it extends about 0.2metres above ground level. Now the indentation looks like the pouring end of a jug with teeth! Cover the indentation with wire gauze to prevent animals or debris from entering the tank.
4. Gradually slope the rest of the 1500sq metres towards the indentation of the tank. This is the collector funnel. Plant grass in this area, if you want to.
5. Security: Erect a small wooden fence around the tank and inlet area. Cover this fence with a thatch, wood, or corrugated iron roof. The fence and roof help prevent birds or roaming animals (including people) from falling into your tank. For additional security, erect another fence (no roof!) around the 2000sq metre area.
6. When rain falls, the collector funnel will direct it towards your underground tank. The grass, if any, will slow down the velocity of water so that it flows gently into the indentation. The grass will also filter small twigs, stones etc. The "teeth" of the indentation futher prevent small stones and other debris from entering the tank. Clean the teeth weekly during the rainy season.
7. Pump the water out. In places with clear skies and heavy rainfalls, sufficient water will collect here for farming purposes and for domestic use. Do not "fetch" water by dipping buckets, pails, etc into the water. This is to prevent contaminating the water. Invest in a handpump or buy a mechanical powered pump. You should charge a small fee for use of this waterworks in order to afford the cost of construction, operation and replacement pumps, etc. It's a business.
COMMENTS:
Static water is a breeding ground for mosquitoes. But do not poison the water by pouring kerosene or insecticide or any other chemicals in the tank to "kill the mosquitoes!". Instead consider putting a wooden or concrete slab directly over the rim of the tank to cut off air supply. The slab should have one to three grooves of 10cm diameter cut into it to allow overflow of the tank. Cover groove(s) with wire gauze. Get that person that calls themselves engineer to help you.
Some places suffer from chemically toxic rainfall e.g places with heavy flaring of gas or burning of waste. The method described in this document for harvesting rainwater will not be appropriate in such places.
Always boil water before drinking or cooking. Se omi kee to mu abi jeun.
Remi-Niyi Alaran writes on enterprise and social capital.
ALARAN DEVELOPMENT ENTERPRISES. Enterprising Communities.
Copyright (c) ALARAN DEVELOPMENT ENTERPRISES, 2003
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