Physics Van 3-site Navigational Menu

Physics Van Navigational Menu

Q & A: Why don't they change salt water into fresh water?

Learn more physics!

Most recent answer: 03/02/2015
Why don't they change salt water into fresh water?
- Angelica (age 13)
Courtice Ontario Canada

"They" do, but it is costly. The process of removing the salt is called desalination, and is a quite common practice in industry, where fresh water is scarce, in Israel and Australia for instance.  And in fact, the fresh tap water is not salty for human consumption, but it still includes some minerals inside, which for some sensitive purposes must be taken away. This is why your kettle needs decalcification from time to time.

One of the simplest approaches is to heat salt water up and collect the saltless vapor. But this obviously demands quite large amounts of energy. Use of fossil fuels is unfeasible for most practices, but factories try to make use of the waste energy radiated by their huge machines. Another approach is to use reverse-osmosis, i.e. selective inability of salt to pass through certain membranes. Nowadays, people are also striving to build sustainable systems, say by utilizing the sunlight to get the water, so that this can be used in large scale, including in agriculture at arid environments. However, best way is to reduce the Homo sapiens population to more sustainable levels and reduce waste of natural resources, so that you will not need to worry about finding alternative resources.


(published on 03/02/2015)

Follow-up on this answer.