When the steam cools and returns to liquid form, it is pure enough to drink. The problem with this method is that it requires a vast amount of energy to produce small amounts of purified water. The expense of the energy has caused most places to seek alternatives other than saltwater distillation. Another new technology used to desalinate water is called reverse osmosis . Though reverse osmosis may sound difficult, the process itself is actually simple.
High pressure pushes salt water through a membrane.
Reverse osmosis is expensive - though cheaper than distillation. Two traditional drawbacks to desalination include the high cost of the energy needed to operate the plants and the safe disposal of the brine. These factors have made researchers find new ways to desalinate water with greater energy efficiency and to dilute the brine and return it safely to the Gulf so that it doesn't harm marine life. Water that currently comes out of the tap costs less than half a penny to produce per gallon. While desalinated water will cost more to produce, it will still cost less than one-half penny per gallon to produce.