Hesperian Health Guides
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There are many kinds of wells for drawing up groundwater. The simplest is a hand-dug water hole, sometimes called a scoophole. The most costly kind of well, called a tube well, is a narrow pipe going deep into the ground with a pump at the top to draw water out.
A well is useful only if people can get water out of it. The best well for any community depends on the depth of the groundwater and the resources available for digging, drilling, and building a well. In many cases, simple shallow wells where people draw water in buckets may be better than costly deep wells that require pumps. Several shallow wells are often better than one deep well, because if one well goes dry, the others can still provide water.
|When people stand on the lip of the well or use unclean buckets, the water in the well can be made unsafe.|
Steps to safer wells and water holes
Before digging a well, make sure it is the best kind of well? for everyone's needs. Well water becomes unsafe if wells are dug:
- too close to pit toilets, sewer pipes, garbage dumping pits, or livestock. Keep at least 30 meters away.
- near industrial activity such as mining or oil drilling, fields where chemical pesticides or fertilizers are used, or waste dumps.
- where waste water or surface runoff can flow into the well.
Shallow hand-dug wells can provide good, safe water. But the water can dry up or be easily contaminated. During rainy seasons, surface runoff may drain into a water hole, carrying germs and other contamination. People or animals who use the water may carry germs on their feet to the water hole. Buckets and ropes around the rim of the well may also collect germs, and can easily contaminate the water when they are lowered into the well.
Simple improvements can prevent contamination. For example, make sure only clean buckets and ropes are lowered into the water. Build up earth around the hole or line the top with bricks or a concrete ring to keep water safer. Lining the hole also makes it less likely to dry up or collapse, and allows for a deeper well that can store more water. (See “Improvements to basic wells and scoopholes” below.)
Before drilling new wells or making costly improvements to water systems, consider making small improvements like these to make your water sources safer.
Improvements to open water holes
|Build stone steps into the water hole so a person can draw water up from a step, without getting wet. Always use the last dry step. Never walk into the water.||
Improvements to basic wells and scoopholes
|1. Unimproved scoophole||2. Mouth of hole built up to keep out runoff|
|3. Mouth closed off with barrel and lid||4. Top strengthened with bricks and small drainage platform|
|5. Protected water hole with drainage platform and runoff channel||6. Protected water hole with drainage platform, runoff channel, and garden|
Protect the family well
Many communities have tube wells or boreholes with pumps built by governments, or local or international agencies. These deep, closed wells protect water from contamination by people and animals. But years after they are drilled, many of these wells can no longer be used because the pumps have broken, or spare parts are no longer available, or the people who knew how to fix them are gone. This results in no regular supply of clean water. People must walk long distances or collect contaminated surface water to fill their needs. In some parts of Africa, protected family wells are replacing tube wells.
A protected well is a hole dug by hand with a lining, a concrete cover, a windlass to raise water, and a drainage platform. Each of these things adds protection to the well. With all of them in place, and with careful handling of the water, a family well can be very safe.
Where to dig a well
When digging a well, the best sign there will be water is when you see other wells nearby. But if the other wells are deep boreholes, the groundwater may be too deep to get to by hand digging. Another good sign is the year-round presence of plants that need a lot of water to survive. Low areas are more likely to have water than higher ground. But if a well is dug in a low area, it will need to be protected from rainwater runoff.
The well lining
In very firm soils, lining the well may seem unnecessary. But it is wise to line at least the top 1 to 2 meters below ground to prevent the side walls from collapsing. If the entire well is lined it will make the water source more dependable, but it will be more difficult to dig the well deeper at a later time. A well can be lined with stones or rocks, with fired bricks, or with concrete.
|Top 1 to 2 meters lined||Fully lined well|
How to make a cover slab for a well
|Make a mold for the slab.|
|Place reinforcing wire
and a mold for the hole
|Pour the concrete slab and
form the protective collar
|Shape the protective collar|
|Set the well cover in place|
Once a well has been lined, the next step is fitting a concrete cover slab. The cover helps prevent polluted wastewater or objects from falling into the well. It also makes the well safer for children and provides a clean place to put buckets as people collect water.
Tools you need: shovel, metal saw, blocks of wood, bucket, rope
- The cover should fit neatly over the upper well lining. Clear a flat place to pour a concrete slab and mark out a circle the size of the cover slab to fit the well. Place a ring of bricks around the marked circle. This ring is the slab mold.
- Leave a hole in the slab to pass a bucket through or to fit a pump. The size of the hole depends on the kind of bucket or pump used, but generally the hole should be large enough for a 10 liter bucket. A tin drum big enough for a bucket to pass through can be used to form the hole.
- Place reinforcing wire (3 mm) within the slab mold to form a grid, with spaces 10 cm apart.
- Remove the reinforcing wire grid and make a concrete mix of 3 parts gravel, 2 parts washed river sand, and 1 part cement. If gravel is not available, use 4 parts washed river sand and 1 part cement. Pour concrete in the mold, halfway to the top. Place the wire grid on top of the wet concrete. Add the remaining concrete and level it with a piece of wood.
- Let the slab cure for 1 hour. Remove the tin drum mold, and fill the central hole with wet sand. Replace the mold on top of the sand and place a ring of bricks around it, leaving 75 mm of space between the bricks and the mold. Fill the space between the bricks and the mold with concrete and let it cure for an hour. After an hour, remove the bricks and the tin mold and shape the protective collar. For the collar to give the best protection, a tin cover should fit snugly over it.
- Let the slab harden overnight and cure for at least 5 days, keeping it wet the entire time. Before putting the slab on a well, test its strength. After it has cured for 7 days or so, place 4 blocks of wood 1 or 2 inches high under the 4 sides of the slab to raise it off the ground. Then dance on it! A well-made slab will not break even with several people dancing on it. Place a bed of cement mortar on the top of the well lining and carefully set the well cover in place.
The windlass, bucket, and chain
A windlass is a shaft fitted with a handle that makes raising the bucket easier and provides a place to wrap the bucket chain or rope. If a pump is fitted to the well later, the windlass can easily be removed. Attach a bucket to the end of the chain or rope. Chain is best because fewer germs will grow on it, but it is costly. Rope is less costly and can be replaced easily if it breaks.
Set windlass supports in concrete on each side of the well.
Cut slots in the poles and place the windlass.
Drive bolts through the posts above the windlass to keep it in place as it turns.
|This design shows wooden windlass supports set in the ground. Windlass supports may also be made of bricks.|
The drainage platform
The drainage platform carries runoff away from the well to a drainage area. This prevents the area around the well from getting muddy, and breeding germs and insects. Germs can grow in cracks, so it is important that the platform is well made.
long if possible
platform and rim should be reinforced with 3 mm wire to prevent it from cracking.
Maintain your well
Well water is easily contaminated when dirty buckets and dirty ropes or chains are lowered into it. To keep well water clean, keep one bucket attached to the well and use it to fill other containers. Washing hands before collecting water and building a fence to keep animals out will also prevent contamination.
Community water tap with drainage
You can also protect your well water when you:
- keep the well cover in place.
- keep the platform and runoff channel clean.
- grease the handle bearing often to make it easier to use.
- do not let children play with the well or pump.
- fence the area to keep livestock out.
- have a person be caretaker of the well.
Drain runoff from wells and taps
Wherever people collect water, water spills. When water collects in puddles, it becomes a breeding ground for mosquitoes that carry malaria and other illnesses. Wells, taps, outlets from storage tanks, and other water collection areas need good drainage to allow spilled water to flow away or to drain into the ground.
To take advantage of water that runs off, plant a tree or a vegetable garden where the water drains. If you cannot plant a tree or garden, make a hollow in the ground filled with rocks, gravel, and sand for the water to seep into. This is called a "soakaway pit." It will help prevent mosquitoes from breeding.
Pumping water from wells
To move water up from a well, a pump is needed. Pumps use various kinds of energy, including electricity, gas, solar energy, or human power. If a pump is difficult to use or if it is often out of service, people will start to collect water from unsafe sources.
How to choose a pump
All pumps have one thing in common: if they break, there is no water. For most people, the best pump is one they can build, operate, and repair by themselves, or that can be repaired by trusted local mechanics. Consider the following when choosing a pump:
- Will it be usable by and meet the needs of both men and women? Were women involved in selecting the community pump?
- What kind of energy source is available? If a pump uses costly fuel, or electricity that is not available, it will not be useful.
- Is the pump easy to repair with available spare parts? Would it be better to have a pump that breaks easily but is very easy to repair locally, or a pump that will break after many years but cannot be easily repaired by local people?
(left a little loose)
strap (holds rope guide together)
The rope pump: a low cost, easy way to lift water
The rope pump is based on an ancient design from China. It is used to pump water from wells up to 15 m deep with little effort. As a person turns the wheel, water is lifted and pours out of a spout at the top of the well.
This pump costs little to make and is easy to fix. The rope is the part most likely to break, but even if it is fixed rather than replaced, the pump still works. People in many countries have adapted rope pumps to fit their needs and the materials they have. (See Other Water and Sanitation Resources.)