Tucson has “hard” water which produces scale in pipes, on faucets, around the sink and shower, film on glass shower doors, and makes washing more difficult because soap doesn’t work as well in hard water. The “hardness” is due to dissolved calcium, magnesium, and iron in the water.
Standard treatment to remove the dissolved minerals include ion-exchange which requires recharge with salt, and reverse osmosis which filters out the offending minerals. If you search the internet, you will find thousands of wesbsites promoting magnetic or electrical wrappings for the water pipes that are claimed to rid you of hard water problems. On February 15, the Arizona Daily Star ran a full-page ad promoting one of these devices.
These products generally include strong magnets or coils of wire that are supposed to induce a magnetic field in the water. These devices do not remove calcium or magnesium (and they so admit). Instead, it is claimed the magnetic (or electrical) fields work by causing the dissolved minerals to “crystallize” or clump together and so remain in suspension rather than adhering to pipe walls and fixtures. It is further claimed that these devices can remove scale already built up in your pipes.
So do these devices really work in home applications? As far as I can find out, laboratory testing shows these devices to be ineffective in home use. In industrial applications, there is some beneficial effect under very specific conditions.
A summary of research is given by Wikipedia:
“Magnetic water treatment (also known as anti-scale magnetic treatment or AMT) is a proposed method of reducing the effects of hard water, as an alternative to water softening. Vendors of magnetic water treatment devices have claimed that powerful magnetic fields can affect the structure of water molecules or the properties of solutes passing through the magnetic field, thus eliminating the need for chemical softening agents. Only the effective hardness is claimed to be altered; no solutes (such as calcium or magnesium) are removed from the water by the process.
Most scientific studies do not support these claims and suggest that magnetic water treatment may be ineffective.”
In 1996, Consumers Reports tested one device promoted for home use. Consumer Reports installed two new water heaters in a staffer’s house. One was supplied with untreated water, the other with water “treated” with a magnetic device. After two years and 10,000 gallons of water, the heaters were cut open and found to have the same quantity and texture of scale. CR reported the tested device ineffective.
Also in 1996, Lawrence Livermore National Laboratory, under contract from the EPA, tested a “commercial device” at a government facility. They found “No beneficial effect was found when using the magnetic device.”
A 2000 report from the Army Corps of Engineers reports on testing magnetic devices. They conclude: “The attached document provides an evaluation of current magnetic water treatment technology. Scientific literature is reviewed and summarized and several devices are tested forscale prevention. In summary the magnetic water treatment devices were not effective for scale control.”
Some other findings from the Corps of Engineers testing:
There is no effect on the rate of pipe corrosion. There were no effects on “measurable water quality parameters.” There was no significant difference in the amount or composition of scaling. “The findings do not support the claims of the manufacturers regarding the ability of their respective devices to prevent mineral scale formation in hot potable water systems.” “There was no discernible effect on the crystalline structure of the scale formed by any of the tested devices.” The crystal structure was tested because some manufacturers claim their devices change the crystal structure of the calcium carbonate into a more benign form.
Another good reference is a 2011 paper by Stephen Lower, a retired physical chemistry professor at Simon Fraser University, Burnaby BC Canada. Note that this paper appeared in Water Technology® Magazine, a trade paper for water treatment professionals. This is a good background article which explains how “hard” water is formed, and treated. Lower’s paper concludes:
“The lack of credible scientific support for the efficacy of present-day PWC [physical water conditioning] devices stands in stark contrast to the claims made by most vendors (and even some users) of these products. Given the potential economic benefits of a widely-applicable chemical-free softening process, especially in arid regions, such as the U.S. southwest, one would expect much more scientific and engineering support for the claims that have been made.”
Lower does note “a study published in a South African technical journal that describes a series of experiments in which one of two parallel heaters was fitted with a permanent magnet device showed scale formation reductions varying over a rather wide range (17-70 percent), with an average of 34 percent.”
“Still, science is never complete, and if qualified investigators could be motivated to follow up on some of the more well-founded leads that have appeared in the literature, it is possible that some of these PWC technologies could be shown to be effective, although almost certainly under very constrained conditions.”
Finally, a short paper from Pennsylvania State University concludes “There is virtually no valid scientific data to support any water treatment benefit from magnetic devices.” And “The claims put forth by manufacturers and sales representatives of these devices are without validity.”
Several of the studies note that scale formation reduction depends heavily on water temperature and flow rate.
My take on all this is: buyer beware.