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Desalination is used to remove salts from brackish or saline surface water and groundwater in order to render it acceptable for human consumption or other uses. Brackish water is defined as having a Total Dissolved Solids content of 1,000 mg/l, and saline water as having 10,000 mg/l. It is increasingly employed to provide drinking-water because of a growing scarcity of fresh water driven by population growth, overexploitation of water resources and climate change. Desalination facilities exist all over the world, particularly in the eastern Mediterranean region, with use increasing on all continents. Small-scale desalination is used to supply fresh water on ships and to provide additional fresh water in some hot and arid regions.
Most present applications of desalination are for estuarine water, coastal water and seawater. Desalination may also be applied to brackish inland waters (both surface water and groundwater) and may be used on board vessels. Small-scale desalination units also exist for household and community use and present specific challenges to effective operation and maintenance.
Desalination/evaporation can be applied on both the household level and the community level (for villages, schools, etc). ===Suitable Conditions===[[Image:Watercone.jpg|thumb|right|3500px200px|Solar distillation: the [http://www.watercones.com/ Watercone].]]
* For use in areas where there are few alternative water sources to the available saline water, therefore before embarking on treatment options for saline water, the first thing to try would be to diversify water sources (e.g. through rainwater harvesting).
[[File:TDS chart.jpg]]
===Resilience to changes in the environment===
====Drought====
'''Effects of drought''': Salinity increases; Corrosion of equipment/pipes.<br>
'''To increase resiliency of WASH system''': Diversify water sources; Household & communal level solar distillation; Managed Aquifer Recharge (MAR); Reduce water-logging in irrigated areas.
===Construction, operations and maintenance===[[Image:DistillationSetup.jpg|thumb|right|350px200px|Click drawing to zoom in.]][[Image:Distillation.jpg|thumb|right|350px200px|Simple distillation and condensation.]]
Of the desalination methods available, the two main ones are: '''distillation''' followed by condensation and '''reverse osmosis'''.
Water produced by desalination is low in minerals and usually aggressive towards materials with which it comes into contact, such as materials used for distribution pipes, storage and plumbing. During post-treatment, the water must be stabilized or re-mineralized prior to distribution to reduce its corrosive nature. Stabilization is commonly achieved by adding chemical constituents such as calcium and magnesium carbonate along with pH adjustment or through blending with small volumes of mineral-rich waters.
===Costs===
'''Solar still costs'''
* Cost can be reasonably high – between £50-£70 (US$70 - US$100) per m2.<br>
* Cost is proportional to output, so there are no economies of scale when scaling up as there are with other treatment methods.
===Field experiences==={|style="border: 2px solid #e0e0e0; width: 40%; text-align: justify; background-color: #e9f5fd;" cellpadding="2"<!--rsr logo here-->|- style="vertical-align: top"|[[Image:akvorsr logo_lite.png|center|60px|link=http://akvo.org/products/rsr/]]||[[Image:akvorsr logo_lite.png|center|60px|link=http://akvo.org/products/rsr/]]<!--project blocks here-->|- style="vertical-align: bottom"|[[Image: rsr 476.jpg|thumb|center|140px|<font size="2"><center>[http://rsr.akvo.org/project/476/ RSR Project 476]<br>Ensure access to safe water and sanitation</center></font>|link=http://rsr.akvo.org/project/476/]] |[[Image: rsr 769.jpg|thumb|center|140px|<font size="2"><center>[http://rsr.akvo.org/project/769/ RSR Project 769]<br>Life-WASH</center></font>|link=http://rsr.akvo.org/project/769/]] |[[Image: rsr 770.jpg|thumb|center|140px|<font size="2"><center>[http://rsr.akvo.org/project/770/ RSR Project 770]<br>title</center></font>|link=http://rsr.akvo.org/project/770/]] |}
==Reference manuals=Manuals, videos, and links==={|align="none"|{{#ev:youtube|c9fepEyGRx8|200|auto|<font size="2"><center>Watercone solar distiller</center></font>}}|[[Image:solar cucumber.jpg|thumb|right|200px|The [http://www.philpauley.com/cucumber.php Solar Cucumber] desalinates sea water and produces drinkable freshwater. As of 2012, the Solar Cucumber is still in the concept phase. Photo: Phil Pauley.]]|}
* [http://www.cawst.org/en/resources/pubs/education-materials/category/25-fact-sheets-academic HWTS Factsheet - Solar Distillation].
* [http://docs.watsan.net/Downloaded_Files/PDF/WHO-2011-Safe.pdf Safe Drinking-water from Desalination] or ([http://apps.who.int/iris/bitstream/10665/70621/1/WHO_HSE_WSH_11.03_eng.pdf alternative link]). World Health Organization, 2011. * [http://www.lboro.ac.uk/well/resources/technical-briefs/40-desalination.pdf Desalination] or ([http://www.washdoc.info/docsearch/title/116234 alternative link]). WEDC Loughborough University. * BLOG: [http://www.core77.com/blog/sustainable_design/eliodomestico_solar_household_still_by_gabriele_diamanti_20893.asp Gabriele Diamanti's "Eliodomestico" solar-powered eco-distiller]. * ARTICLE: [http://www.nytimes.com/2011/03/22/business/energy-environment/22iht-rbog-technology-22.html?scp=1&sq=New+Technology+Could+Make+Desalination+More+Accessible&st=nyt# New Technology Could Make Desalination More Accessible]. New York Times. * The [https://changemakers.org/sites/default/files/waterpyramid%20brochure%20mrt%2008.pdf Water Pyramid] by Aqua-Aero WaterSystems. ===Acknowledgements===* CARE Nederland, ''Desk Study : [[Resilient WASH systems in drought -prone areas]].'' October 2010. * [http://wwwdocs.googlewatsan.comnet/Downloaded_Files/PDF/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDAQFjAB&url=http%3A%2F%2Fwhqlibdoc.who.int%2Fpublications%2F2011%2F9789241548151_engWHO-2011-Guidelines.pdf&ei=RlCHT5-jGeOiiQL5xKmLAg&usg=AFQjCNGx2Q3Rc5yFmbygAIgmJOjg5CSp7g&sig2=C9T9N9V9nUigsjUZtqMR5w ''Guidelines for Drinking-water Quality''], fourth or ([http://apps.who.int/iris/bitstream/10665/44584/1/9789241548151_eng.pdf alternative link]). Fourth edition. World Health Organization (WHO), 2011. * Smith, Michael, and Shaw, Rod. [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CDEQFjAA&url=http%3A%2F%2Fwww.lboro.ac.uk%2Fwell%2Fresources%2Ftechnical/well/resources/technical-briefs%2F40/40-desalination.pdf&ei=zFuHT-2kIJHYiQLUy4myAg&usg=AFQjCNEhxN_0q4aUgKOuu1ep8fUxBp4Cig&sig2=mdlJUIaqoJdLexf7TVT0Yw ''Desalination'']or ([http://www.washdoc.info/docsearch/title/116234 alternative link]). WEDC Loughborough University.