One way to get fresh water from salt water (second reading)

Necessary to obtain purified water, desalination plants are built near the coast to take seawater and other brackish waters. Drinking water is obtained through two systems: either with membranes or with steam
 For example in Canary Islands ,  Where do they get drinking water? ...
Nowadays people have investigated a lot of abou it  , so they found ---> DESALINATION PLANT(This membrane is a thin film made of polyamide, which is a petroleum derivative that allows water through but not salt.The first thing is to catch the water for in wells near the coast, from which is pumped to a plant. Once here, the water is filtered several times in a large appliances.)
This machine is very helpfull but is too expensive, maybe in some countries tha are excellent in the economic aspect could buy this membrane but in PERÚ , I think that is so far of our imagination.

WE COULD DO THAT IF THE GVERMENT START TO THINK MORE ABOUT THE FUTURE AND THE PROBLEMS IN THE ENVIROMENT ..