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Flooding of wells often results in contamination of freshwater. Specialized construction design and planning procedures can be used to protect wells against the risks of flooding, and consequent water contamination.
Specific measures include sealing wells with a protective cap (such as concrete or clay) extending several metres below the surface to provide a protective barrier for the upper part of the well. This mitigates contaminant infiltration and improves the well’s strength, reducing the risk of collapse during a flooding event. Additional measures include installation of hand pumps at an elevated level that are watertight following use. More advanced wells may be equipped with systems that send a warning if surface water enters the well, prompting a response to reduce health risks, for example prohibiting use of the well or setting up a temporary water treatment site.
Selecting the right site for a well can also reduce water contamination risks. Constructing wells on higher ground, an adequate distance uphill from potential contamination sources (e.g. latrines, fertilized fields) reduces the pollution risks of during flood events. Tube-wells (a pipe or tube bored into an underground aquifer) and boreholes (narrow shafts bored into underground aquifers) are also generally less susceptible to contamination compared to dug wells (hand dug holes leading to a groundwater supply), due to use of a smaller diameter bore that is encased with a protective tube.