[[Image:evap desal icon.png|right|100px80px]][[Image:SolarDistiller.jpg|thumb|right|250px200px|Gabriele Diamanti's "Eliodomestico" solar-powered eco-distiller. The small, vat-like still is made entirely from terracotta and zinc-plated metal sheets. It is designed to be produced (and eventually repaired) by local craftsmen.]][[Image:water pyramid.jpg|thumb|right|250px200px|The [http://www.aaws.nl/index.php/products WaterPyramid] is used in tropical remote regions to desalinate saline water and to harvest rainwater. The technology is best used were abundant radiation of the sun and free ground space is available. Photo: Aqua-Aero WaterSystems.]]__NOTOC__<small-title />
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.
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|250px200px|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|250px200px|Click drawing to zoom in.]][[Image:Distillation.jpg|thumb|right|250px200px|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="width: 70%; text-align: justify; background-color: #f5f5f5;"
|[[Image:rsr 476.jpg|thumb|none|200px|<font size="2"><center>Project 476</center></font>|link=http://www.akvo.org/rsr/project/476/]]
|}
===Manuals, videos, and links===
{|align="none"
|{{#ev:youtube|c9fepEyGRx8|200|auto|<font size="2"><center>Watercone solar distiller</center></font>}}
* The [http://www.aaws.nl/index.php/products Water Pyramid] by Aqua-Aero WaterSystems.
===Acknowledgements===
* CARE Nederland, Desk Study: [[Resilient WASH systems in drought-prone areas]]. October 2010.
