Sea Water can be desalinated in order to be converted to fresh water suitable for human consumption or irrigation. Large-scale desalination typically uses large amounts of energy as well as specialized, expensive infrastructure, making it very costly.  However, according to MSNBC, a report by Lux Research estimated that the worldwide desalinated water supply will triple between 2008 and 2020.

Current trends in desalination are focused on developing cost-effective ways of providing fresh water for human use.  Desalinization can be a viable solution to regions where the availability of water is limited. Middle Eastern countries where water scarcity is an issue, along with the large energy reserves, have led to extensive construction of desalination plants.

The world's largest desalination plant is capable of producing about 2500 gallons of water per second. This plant is called the Jebel Ali Desalination Plant and is located  in the United Arab Emirates. It is a dual-purpose facility that uses multi-stage flash distillation and desalination plant.  In the United States the largest  plant is located in Tampa Bay, Florida, which began desalinizing 25 million gallons (95000 m³) of water per day in December 2007.[6] The Tampa Bay plant runs at around 12% the output of the Jebel Ali Desalination Plants. According to the International Desalination Association, “World-wide, 13,080 desalination plants produce more than 12 billion gallons of water a day,”

There are many environmental considerations of ocean water desalination plants.  One major one is the impact of the open ocean water intakes and the ongoing impacts on marine life.  Alternatives including beach wells that eliminate this concern.  These solutions require more energy, increase initial financial costs and limit output. Other concerns include the highly concentrated waste product that was removed (Brine), air pollution and greenhouse gas emissions from the power plants that electricity and thermal energy to the desalination plants.  Much of the Brine is classified by the United States Environmental Protection Agency as industrial wastes.

In the past many novel desalination techniques have been researched with varying degrees of success. Some, such as Forward osmosis are still on the drawing board now while others have attracted research funding. For example, to offset the energy requirements of desalination, the U.S. Government is working to develop practical solar desalination.

As an example of newer theoretical approaches for desalination, focusing specifically on maximizing energy efficiency and cost effectiveness, Passarell Process may be considered.  Other approaches involve the use of geothermal energy. From an environmental and economic point of view, in most locations geothermal desalination can be preferable to using fossil groundwater or surface water for human needs, as in many regions the available surface and groundwater resources already have long been under severe stress.

Recent research in the U.S. indicates that nanotube membranes may prove to be extremely effective for water filtration and may produce a viable water desalination process that would require substantially less energy than reverse osmosis.

On June 23, 2008 it was reported that Siemens Water Technologies had developed a new technology that desalinizes one cubic meter of water while using only 1.5 kwh of energy, which, according to the report, is one half the energy that other processes use.

Investing in water desalination and water treatment may include investments in desalination plants or the companies that manufacture desalination equipment.  It may also include investment into companies that perform the contracting on desalination plants.