by Nick Gromicko, CMI®
Hand-dug wells are ground excavations and their associated structures used to access groundwater in underground aquifers. Until modern times, all artificial wells were hand-dug.
- Hand-dug wells are still the most common means of collecting water in certain parts of the developing world.
- The historical indispensability of hand-dug wells has made its way into important literary references, including the Bible’s story of Jesus meeting a woman at Jacob's well, and even a nursery rhyme called "Ding Dong Bell" about a cat in a well.
- Long ago, manual well-digging was a profession enjoyed by workers of small stature who could fit in a confined space. They used simple tools, such as picks and short shovels.
- Britain’s Woodingdean Well, at a depth of 1,285 feet, is the deepest hand-dug well in the world. Generally, however, they are much shallower than their drilled counterparts.
Advantages of Hand-Dug Wells
- The familiar postcard image of a hand-dug well, together with an above-ground wall and a bucket lowered by rope into the well, adds a rustic charm to a yard. Its aesthetic appeal may even increase the property value.
- Hand-dug wells are inexpensive and low-tech compared to standard drilled wells. A bucket and rope have worked for thousands of years.
- Their large diameter is exposed to a correspondingly large area of the aquifer. Hand-dug wells are suited to obtain water from less-permeable soils, such as fine clay, sand and silt.
- They can be made deeper easily. By contrast, when the depth of a drilled well becomes insufficient due to increased demand or a lowered water table, it may cost the homeowner tens of thousands of dollars to deepen the well.
- A hand-dug well's operational and maintenance costs are low.
- Construction can incorporate community participation, as digging does not require skilled labor.
Disadvantages of Hand-Dug Wells
- They are not suited to rocky or exceptionally hard ground.
- Their construction can be dangerous due to collapsing soils, falling objects, and asphyxiation of workers inside the well.
- Their construction is labor-intensive and can take a long time.
- They are easily contaminated by surface runoff.
- Their ability to deliver water for the demands of a modern household, in terms of both quantity and flow rates, is limited.
Construction Safety Considerations
Building a hand-dug well can pose serious safety hazards, such as the following:
- collapse of the sides, which can kill a worker if he's in the well when it collapses;
- objects that fall into the well from the surface above, which can seriously injure workers in the well; and
- a lack of oxygen in the well.
Hand-dug wells are typically constructed during dry weather for several reasons: the water table will be at or near its lowest level, allowing the required depth to be adequately determined; and dry soil is less likely to collapse during excavation.
Wells should be placed where large supplies of clean groundwater are likely to be available. Water may be delivered using a rope and bucket, but these components are usually mere stylistic elements, while water is typically collected using a modern pump. A layer of gravel may be placed at the bottom to prevent the soil from silting up. Any concrete used should be properly mixed and allowed to cure to ensure its strength and longevity.
Protection against cave-ins should be a concern during construction of hand-dug wells, especially in unstable soil. Workers can excavate within pre-cast concrete rings that later become the permanent lining to the well's sides. Vertical, close-fitting timber boards supported by steel rings may also provide protection against cave-ins.
Safety Considerations for Use
- People and animals can fall into the well, where they may become trapped or drown. Prevention against this hazard is two-part:
- provide an above-ground wall around the well to prevent children and animals from falling into the well; and
- provide a child-safe, heavy, secure cover at ground level. Inspect the cover periodically for decay, corrosion, and anything that may make it weak.
No one should be allowed to enter the well without a safety harness and supervision.
- Direct the surface runoff away from the well, and test the water frequently for potability and for surface-borne water contaminants. To do this:
- make sure that the well is located upstream of potential pollution sources, such as pit latrines, gas stations, rubbish pits and burial grounds;
- prohibit surface pollution at the well site; and
- ensure that any spaces between the well's structural concrete rings are filled in with concrete.
In summary, hand-dug wells pose unique challenges, but when properly constructed, maintained and inspected, they can be picturesque and advantageous.