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==Suitable conditions==
* Layers of sand and gravel tend to provide good locations for wells and boreholes. Other good locations are in weathered rock in granite areas, along the edges of valleys in mountainous areas or in a river valley where there may be sandy deposits under the banks.
* Care should be taken to avoid siting wells in perched aquifers (shallow aquifers with limited recharge capacity and water storage).
- Water levels in the aquifer can drop over time, resulting in possible mining (where aquifer is compressed and cannot hold water any longer afterwards)
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==Resilience to changes in the environment==
====Drought====
'''Effects of drought''': Can dry up perched aquifers; Groundwater levels dropping in perched aquifers.
'''Underlying causes of effects''': Less recharge of aquifer due to less rainfall; Increasing population & water demand; Size of aquifers – e.g. perched aquifers will be used up faster; Wells not dug deep enough into water table.
'''To increase resiliency of WASH system''': Avoid perched aquifers; Dig wells deeper – de-water well during caissoning within the water table; Allow for subsequent deepening by using telescopic lining; Dig wells during the latter half of the dry season; Recharge aquifer through Managed Aquifer Recharge (MAR) boreholes; Jet in the bottom of the well to provide a means of faster recharge; Increase flow by use of porous concrete or perforated pointed steel pipes driven horizontally into the aquifer.
==Construction, operations and maintenance==
'''General advice on cement''': A common cause of cracks in structures and linings (e.g. in tanks, dams, waterways, wells) is errors in mixing and applying the cement. First of all, it is important that only pure ingredients are used: clean water, clean sand, clean rocks. The materials have to be mixed very thoroughly. Secondly, the amount of water during mixing needs to minimal: the concrete or cement needs to be just workable, on the dry side even, and not fluid. Thirdly, it is essential that during curing the cement or concrete is kept moist at all times, for at least a week. Structures should be covered with plastic, large leaves or other materials during the curing period, and kept wet regularly.
'''Specific advice''':
[[Image:HandDugWelldiagram.jpg|thumb|right|350px|]]
[[Image:HandDugWellConstruction.jpg|thumb|right|350px|Construction of hand dug well at Kulala Kebele, Dera Woreda, Amhara Region, Ethiopia.]]