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I'm extremely skeptical of the idea of magnetic water softeners (strong magnets attached to pipes), but desperately wish it were true because I hate lugging 40# bags of salt out to my well house in the hot Texas sun.

I'd love to see some objective research results on the subject from someone who isn't selling a magnetic water softening system.

For the purposes of this question, "work" is defined as changing the properties of water treated with the system to:

  1. Substantially improve the effectiveness of soap products using the output water.
  2. Minimize scale buildup on fixtures, in pipes, and on dishes.

The reason I'm being so specific is that I've seen some defenders of this technology that claim you get the benefits of soft water using their systems, but because of the way it works it doesn't show any difference on standard water hardness tests. That is, it is pseudo-soft water, but acts like soft water for all practical purposes. Just the fact that they have a miracle solution, that involves magnets, and is resilient to empirical testing makes me extremely skeptical.

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See also skeptics.stackexchange.com/questions/162/… –  Suma Jun 6 '11 at 9:13
“acts like soft water for all practical purposes” – then what do the water hardness tests measure? –  Konrad Rudolph Jun 6 '11 at 9:31
I wonder if you could add iron filing to the water heat it enough for the calcium to build up on the iron filings and then use a magnet to pull them out of the stream. Although you would then be dragging bags of iron filing around instead of bags of salt, have greaters costs as you heated the water and have to folter the water to make sure no iron filings got through to the tap... –  Ardesco Jun 6 '11 at 10:23
I don't think the claim is to eliminate the hardness but to render it unable to clog pipes or do other damage. I can find no documentation of this claim. –  user9082 Nov 2 '12 at 12:05
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3 Answers

up vote 32 down vote accepted


There have been a few studies on the efficacy of magnetic water softening systems. This one (PDF) from the Lawrence Livermore National Laboratory compares chemical and magnetic systems against a control. The table of results for scale buildup are pretty compelling:

enter image description here

As you can see, the Polyphosphate chemical process was effective, and the magnetic one was not.

The Army Corps of Engineers also conducted a study on three magnetic water softening devices which found:

The results of this study do not indicate any clear advantage for any of the three devices tested versus a control for the inhibition of mineral scale formation or the corrosion of copper.

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At this question, it is explained how conventional water softener based on salts work. The explanation will also make it clear why magnets won't do anything: The compounds have to be altered chemically. The substances in question are not susceptible to magnetism (well, in theory, everything is susceptible to magnetism, but only for the time that the magnet is applied).

Hence, these objects are completely lacking a plausible mechanism for why they should work.

While this does not negate that they could work (and in the process prove much of what we know about physics to be wrong...), the burden of proof is with someone marketing that device. And, oh magic, they claim that their water is undistinguishable from hard water. So what, then, is the difference? Soft for all practical purposes means, for example, not leaving limescale residue behind. That is a simple chemical thing to test for.

I am actually quite sad that people can be so dense to fall for an "invisible intangible dragon, breathing undetectable fire, living in my garage"

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Presumably, magnetic water softeners are intended to "attract" metal ions dissolved in water. It would be interesting to see if an electrostatic water softeners (which would actually attract dissolved ions) exist or work as well as chemical ones. –  crasic Jun 6 '11 at 6:39
It is sad, but I don't blame people that fall for this. Most people probably don't understand how a traditional water softener works either, and the fact that so many magnetic ones are on the market might imply to them that they are mainstream and thus effective. –  JohnFx Jun 6 '11 at 16:04
@crasic The rationale behind that would be the force a magnetic field exerts on a moving electric charge. The force is perpendicular to the direction of flow and the magnetic field lines. But: There is still the force of the flowing water, and once a certain number of charges has accumulated on one site, their repelling electrostatic force will cancel the magnetic force. (See Hall effect for something similar) –  Lagerbaer Jun 6 '11 at 16:39
maybe the magnetic filter will work if someone puts a silly hologram on it, therby upping its functionality by the voodoo x nonsense + woo = net financial loss equation. –  Monkey Tuesday Jun 7 '11 at 6:57
Please provide some references to support your claims. –  Sklivvz Jun 14 '12 at 6:59
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This post does not cite any references or sources. Please help improve this post by adding citations to reliable sources. Unsourced material may be challenged and removed.

There was a study by Trinity College that concludes there is 99.9% chance that a magnetic water softener will reduce hardness to some degree, very interesting how it happens.

Carbonates formed by heating water containing ≈120 mg(Ca)/l are characterized by X-ray diffraction and electron microscopy. Tests on 32 pairs of samples establish, at the 99.9% probability level, that drawing water through a static magnetic field (B≈0.1T, ∇B≈10 T/m) increases the aragonite/calcite ratio in the deposit. There is an incubation period of several hours, and memory of magnetic treatment extends beyond 200 h.

Source: Cass, S., & Coey, J.M.D. (2000). Magnetic water treatment. Journal of Magnetism and Magnetic Materials, 209, 71-74. (Full text - PDF)

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Can you please include an excerpt? –  Sklivvz Jun 12 '12 at 23:25
It doesn't say that it reduces hardness at all. It says "In conclusion, we have established that a magnetic field effect exists. Passing water through a magnetic field subsequently favours formation of aragonite rather then calcite in our experiments" where aragonite is a different crystalline structure of calcite. In particular, Table 1 specifically says that there is no effect on Na, Mg, K and Ca, which are the dominant cations that make water "hard" –  msw Jun 14 '12 at 0:04
This is an unsound conclusion. A significance level of 0.001 does not mean the same as 99.9% likely. –  Oddthinking Jun 15 '12 at 1:44
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