A thousand gallons of freshwater from a desalination plant costs the average US consumer $2.50 to $5.
The high cost of traditional desalination is driven by the price of energy for high-pressure systems and the capital cost of high-pressure pumps and seals. Today, recovery of capital and electric power add up to as much as 73% of the cost of desalinated water. Fresh water scarcity and cost-effective desalination. The scarcity of fresh water is an increasingly serious problem around the world due to growing populations and diminishing supplies of fresh water. Desalination could help alleviate these shortages, but it has traditionally been an extremely expensive process. The Costs and Benefits of Desalination 167 140% 120% 3 Relative Annual Cost per m 100% 80% 60% 2-Stage Seawater RO with Conventional Pretreatment 40% 20% 0% -30 -20 -10 0 10 20 30 40 50 60 % Change in Baseline Operating Pressure FIGURE 6-9. The Costs and Benefits of Desalination 169 technologies as illustrated in Table 6-2. Such costs are very significant, each representing over one-third of annual cost for a 189,000 m3/day seawater RO facility (Figure 6-6). By 2014, Israel's desalination programs provided roughly 35% of Israel's drinking water and it is expected to supply 40% by 2015 and 70% by 2050. As of May 29, 2015 more than 50 percent of the water for Israeli households, agriculture and industry is artificially produced. A minimum energy consumption for sea water desalination of around 1 kWh/m 3 has been determined, excluding prefiltering and intake/outfall pumping. Under 2 kWh/m 3 has been achieved with existing reverse osmosis membrane technology, leaving limited scope for further energy reductions. 172 Desalination: A National Perspective the cost of existing water supplies. In spite of this fact, the addition of desalinated water is often paid by incremental increases in the price of water paid by users. The San Diego Water Authority is a case in point. Existing rates are approximately $0.24/m3 ($300/ a.f.). The Costs and Benefits of Desalination 169 technologies as illustrated in Table 6-2. Such costs are very significant, each representing over one-third of annual cost for a 189,000 m3/day seawater RO facility (Figure 6-6). Aside from the financial cost of desalination, it’s a very energy intensive process. According to this article on LiveScience, current desalination methods consume around 14 kilowatt hours of energy to crank out 1,000 gallons of desalinated water. The typical Australian uses somewhere in the region of 100 gallons a day (about 400 – 500 litres). USA consumption rate is pretty much the same So, what is holding us back from diving in headfirst? Until recently, purifying seawater cost roughly five to 10 times as much as drawing freshwater from more traditional sources [source: USGS ]. RO filters have come a long way, however, and desalination today costs only half of what it did 10 to 15 years ago. Energy consumption accounts for as much as one-third of the total cost of desalinated water, making even coastal plants expensive to operate [source: Maloni, NRC-WSTB ]. Inland states must also grapple with the sizeable expense of transporting seawater inland Desalinated water typically costs about $2,000 an acre foot -- roughly the amount of water a family of five uses in a year. The cost is about double that of water obtained from building a new reservoir or recycling wastewater, according to a 2013 study from the state Department of Water Resources. The crews are building what boosters say represents California's best hope for a drought-proof water supply: the largest ocean desalination plant in the Western Hemisphere. The $1 billion project will provide 50 million gallons of drinking water a day for San Diego County when it opens in 2016. Given the high costs of freshwater importation and reclamation, desalinating seawater is an increasingly attractive option for water-stressed areas. The potential for desalination is limited mostly by social, political, environmental and economic considerations, which vary from place to place. Energy consumption accounts for as much as one-third of the total cost of desalinated water, making even coastal plants expensive to operate [source: Maloni, NRC-WSTB ]. Inland states must also grapple with the sizeable expense of transporting seawater inland But desalination is expensive. A thousand gallons of freshwater from a desalination plant costs the average US consumer $2.50 to $5, Pankratz says, compared to $2 for conventional freshwater. 
http://tech.uchicago.edu/learn/features/20130307_desalination/ http://www.nap.edu/read/12184/chapter/8 https://en.wikipedia.org/wiki/Desalination http://www.nap.edu/read/12184/chapter/8 http://www.greenlivingtips.com/eco-news/The-cost-of-desalination.html http://adventure.howstuffworks.com/survival/wilderness/convert-salt-water2.htm http://www.mercurynews.com/science/ci_25859513/nations-largest-ocean-desalination-plant-goes-up-near http://adventure.howstuffworks.com/survival/wilderness/convert-salt-water2.htm http://www.pri.org/stories/2015-05-15/desalination-expensive-energy-hog-improvements-are-way
cost of desalination