How Do You Remove Salt from Water?

Separating Salt from Water

If you needed to, you could remove salt from seawater.
If you needed to, you could remove salt from seawater. John White Photos / Getty Images

I've been asked "How do you remove salt from water?" enough times that I suspect finding the answer to the question is a common science assignment. So... how do you do it?

You can boil or evaporate the water and the salt will be left behind as a solid. If you want to collect the water, you can use distillation. One way to do this at home would be to boil the saltwater in a pot with a lid. Offset the lid slightly so that the water that condenses on the inside of the lid will run down the side to be collected in a separate container. Congratulations! You've just made distilled water. When all of the water has boiled off, the salt will remain in the pot. Evaporation works the same way, just at a slower rate.

To evaporate water to obtain salt, place the salt water in a wide, shallow dish. This shape offers maximum exposed surface area, which aids evaporation. You can speed up the process by placing the dish in a warm, sunny window or by blowing a fan over it. If you place it outdoors, evaporation is quick on a warm, sunny, breezy day. It will be slower on a cloudy, cold, or humid day.

Crystallizing salt from salt water doesn't leave behind pure water, although it does remove a lot of the salt. The remaining liquid will be a less-than-saturated solution.