Environmental Science: How to Create Fresh Water

Environmental scientists know that in some regions of the world, even practicing water conservation can’t meet all the freshwater needs of people and ecosystems. The Middle East, in particular, faces extreme water scarcity and water stress.

One approach to dealing with these issues is desalinization, the process of removing salt from salt water to create fresh water. Scientists have developed two ways to achieve desalinization:

• Distillation: Scientists heat the salt water enough that the water molecules evaporate, leaving the salt behind. The scientists then cool the evaporated water, or steam, so that it condenses into a salt-free liquid. The figure illustrates this process.

  

  Credit: Illustration by Wiley, Composition Services Graphics

• Reverse osmosis: Scientists expose the salt water to increasing pressure, which forces the water to move through a membrane. The membrane allows water molecules to move through it while blocking the salts. Like a filter, the membrane removes the salt and produces fresh water. This figure shows what this process looks like.

  

  Credit: Illustration by Wiley, Composition Services Graphics

The growing human population will need increasingly more fresh water to meet its needs. Ensuring that every person and ecosystem has as much fresh water as they need will require a combination of water conservation and desalinization technologies.