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Q & A: Magnets for removing minerals from hard water

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Most recent answer: 01/14/2015
Can magnetis be used to remove minerals from "hard" water? Is there a simple procedure for classroom use?
- Jacob (age 12)
Hi Jacob,

No, I do not think you can use magnets directly to remove minerals from hard water. A common mineral which makes water hard is Calcium carbonate, and it is not particularly magnetic. You might employ a magnet and a coil of wire and an energy source (like a steam turbine) to generate electricity to remove minerals by distillation or by electroplating them out, but that sounds like a roundabout use of magnets in this case.

Sometimes water gets little bits of rust suspended in it making it look brown and yucky. Magnets may have some use in attracting rust particles, but I wouldn’t count on spectacular performance there.


(published on 10/22/2007)

Follow-Up #1: can magnets descale pipes?

But then whyare magnets used to descale the pipes.
- Salil D Save (age 43)

I was about to answer that only the reason is that some people want to make money by selling the magnets, but it seemed a good idea to check if there were any reliable information first. I found a paper co-authored by Michael Cooey, a very good researcher in the field of magnetic materials, in which the authors demonstrate an effect of magnetic fields on the formation of mineral crystals from hard water. 
(Magnetic water treatment. J.M.D. Coey, Stephen Cass.
Journal of Magnetism and Magnetic Materials 209 (2000) 71-74)()

The paper suggests some possible mechanisms, which the authors acknowledge are not particularly compelling. Assuming that the effect is real, it's not clear over what range of conditions it would be useful. The effect described in the paper might assist in preventing scale formation, but it's hard to see how it would remove scale.

Mike W.

posted without vetting until Lee returns

(published on 01/14/2015)

Follow-up on this answer.