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[[Image:Wells,_shafts,_and_boreholes_icon.png|right|80px]]
[[Image:RechargePit.jpg|thumb|right|200px|Recharge pit constructed for recharge of surface runoff. Rajasthan, India. <br> Photo: [http://unesdoc.unesco.org/images/0014/001438/143819e.pdf ''Strategies for Managed Aquifer Recharge (MAR) in semi-arid areas.''] UNESCO.]]
In loosely consolidated material, recharge pits and trenches are also used in cases where low permeability material overlies the aquifer, which occurs at trench-able depth, approximately 5-15m. Structures are excavated sufficiently deep to penetrate the low permeability strata, in order to provide direct access to the aquifer. Trenches or pits can be built to maximise the side-wall surface area and minimise the bottom surface area in order to facilitate horizontal movement of recharge water into the aquifer. The facilities should ideally be covered to keep out sunlight, animals, and people.
===Suitable conditions===
* Site only in areas where rainwater does not infiltrate fast enough where there is high runoff.
* '''Avoid''' where there is a risk of chemical contaminants entering the well, e.g. fertilizers and pesticides from agriculture, and when the final
===Resilience to changes in the environment===
====Drought====
'''Effects of drought''': Water levels reduce in wells & boreholes that are being recharged. <br>
Shallow wells in areas with a high water table are more prone to contamination from flooding than deep boreholes. Wells near rivers can be contaminated and filled with sand during flash floods.
===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.
[[Image:RoofToAquifer.jpg|thumb|right|300px|Roof to aquifer recharge. Click image to zoom. <br> Drawing: Unicef/Ara Centro. (2009)]]
Some chemical pretreatment of the water may be required to prevent flocculation of iron, CaCO3, etc. and chlorination of other disinfection may be needed to prevent microbial growth. Clogged wells may need to be recovered at regular intervals using surging and pumping to remove fines and bacterial growth physically and the use of a wetting agent to remove air in an air-clogged well. Carbonate aquifers exhibit the least amount of clogging due to the gradual dissolution of calcite by a slightly acidic injectant, if periodic backflushing is observed.
===Manuals, videos, and links===
* [http://www.trust.org/alertnet/news/namibian-capital-needs-water-banks-for-dry-times Namibian capital needs "water banks" for dry times]. Reuters. 26 Oct 2011.
* [http://www.ewisa.co.za/literature/files/087.pdf Planning Water Resource Management: The Case for Managing Aquifer Recharge], by E.C. Murray and G. Tredoux.
* Commercial product: [http://www.kentainers.com/wp-content/uploads/2013/01/Permawell.pdf PERMAWELL]. Made by AquaSanTec.
===Acknowledgements===
* CARE Nederland, Desk Study: [[Resilient WASH systems in drought-prone areas]]. October 2010.
* Gale, Ian, [http://unesdoc.unesco.org/images/0014/001438/143819e.pdf Strategies for Managed Aquifer Recharge (MAR) in semi-arid areas.] UNESCO's International Hydrological Programme (IHP), 2005.
* [http://www.uniteforsight.org/environmental-health/module4 Water: The Water Crisis.] Unite for Sight.