Magnetic water treatment
Do you live in a hard water area?
Are you bothered by limescale buildup?
Bored with paying big bucks for chemical water softners?
Then Magnetic Water Treatment is what you're looking for!
 The sales pitch
Simply by attaching high powered magnets to your water supply you can reduce water hardness and, according to some sites, even reduce limescale buildup. To anyone living in a hard water area this sounds like a godsend — no more furred up kettles. To give credibility, the sites may even link to 'proper' scientific papers like Magnetic Water Treatment. J.M.D. Coey and Stephen Cass, J. Magnetism Magnetic Materials 209 (2000) 71-74 or A. Szkatula, M. Balanda, M. Kopec. European Physical Journal — Applied Physics 18 41-49 2002. As ever with science woo there's plenty of testimonials from grateful customers who declare that within days of fitting magnets to their water supply their kettle was free of limescale.
 The reality
Websites selling these devices charge exorbitant amounts of money for what amount to magnets with clamps, which if one really wants to try it could be constructed for much less using neodymium magnets. The fallacy of "higher price = more effective" may be in play here as well. One cited paper claims a magnetic water treatment alters calcite deposits in water to aragonite. The intended implication may be that aragonite behaves differently and causes less scale buildup, yet calcite and aragonite are both CaCO3 so it is unclear how this actually would work.
We must also keep in mind that no ordinary fluid can be magnetized, due to the fact that the molecules move too much for their magnetic poles to stay aligned. Ferrofluids don't count because they're colloidal suspensions of ferromagnetic nanoparticles, usually suspended in some kind of mineral oil that would be extremely toxic if swallowed.
Whilst there have been studies that have shown a possible connection between magnetic treatment of water and calcium deposits it should be borne in mind that:
- Studies showing no effect far outweigh studies showing a positive effect.
- No one has come up with a convincing explanation of why this works.
- Given the vast costs associated with calcium deposits in industrial applications if this were to work it would be the industry standard.
Activated charcoal filters (e.g. Brita) have the advantage of price and, oh, yes, of actually working, and by a known mechanism. Just the thing for living in London or Adelaide. Say goodbye to limescale flakes in your tea!
 See also
- ↑ Ferrofluids are usually used as lubricants for moving magnetic parts (the magnet keeps the oily ferrofluid in place), as airtight hard drive seals (the fluid, when trapped between magnets, makes a completely impenetrable seal), and as magnetic coil coolant (due to Curie's law, ferrofluids lose their magnetism at high temperatures, which means the hot ferrofluid flows away from the coil as it loses its magnetism, and is replaced with colder, more magnetic, ferrofluid).