How is desalination different from water reclamation?

1 Answer
Jul 9, 2016

Reclaimed water is basically just filtered. Desalinized water needs a bit more work.


In the movie Waterworld, there is a scene where Kevin Costner's character apparently urinates into a glass, puts the liquid through a hand-cranked water reclamation device, and winds up with a glass of clean drinking water which he promptly drinks. He is out on the ocean in a boat and one might wonder why he didn't hand-crank some of that plentiful seawater instead. There is a reason.

Reclaiming water from sewage sounds pretty disgusting, but with filtration and some chlorination, it's actually a rather simple process and has been done successfully and cheaply in many parts of the world. A micro-filter requires almost no energy costs.

Desalination is a bit more involved. Salt can't just be filtered out or chemically neutralized; it has to be boiled and evaporated to separate out the salt. Also, sea water is loaded with ionized atoms, and getting rid of those via reverse-osmosis is prohibitively expensive.