I have recently received an ad for a device attaching to my inlet water pipe and a power socket, and claiming to massively reduce the scale build-up.

This compact, computerised limescale remover uses a coil wrapped around the outside of your main intake pipe to create an electronic force, which changes the physical properties of the scale-forming calcium.

Those limescale beasties are literally shocked into shape. Scalewatcher electronically alters the shape of the limescale crystals so they can't stick onto your pipes any more. Instead they just wash straight through your system.

Your water doesn't just stop depositing limescale anymore — it actually absorbs and dissolves existing limescale, so, over time, Scalewatcher actually helps to clean up your plumbing!

I can't think of any mechanism through which it could possibly achieve that, although my knowledge of physics is amateur-level. Could it work?

(It does seem to trigger all the "scam" alarms in me, but now I have a good place where to seek a second opinion!)

P.S. Curiously, it is claimed that the water remains chemically unchanged - which is weird because any device that actually succeeds at reducing the scale buildup will necessarily increase the amount of minerals in the tap water...

  • are you referring to that Hydrocare thing they advert at 5 am?
    – mfg
    Commented Feb 25, 2011 at 20:54
  • @mfg no, but while scanning the ad I noticed that they have a website: scalewatcher.co.uk
    – RomanSt
    Commented Feb 25, 2011 at 21:14
  • 3
    By now I've found so many hints that it's a scam that I decided to report it as such. In particular, it costs over £200, whereas the only thing it can possibly do is pass (a very small amount of) specially modulated current through that coil. I know it's a small amount because it "costs £3 per year in electricity".
    – RomanSt
    Commented Feb 25, 2011 at 21:35

3 Answers 3


I have met with a similar device in a form of either permanent magnet or an electro-magnet. In both cases the devices failed when subject to an experiment:

Scientific and engineering studies generally refute the effectiveness of the method, finding no differences not attributable to other causes between systems with and without a magnetic water treatment device, and no theoretical basis to expect that there might be. Vendors frequently use pictures and testimonials to support their claims, but omit quantitative detail and well-controlled studies.

In this case the description "how it works" is quite similar, using physical terms very vaguely, which gives impression of scientific approach to a buyer, but actually tells nothing at all. How it "increases the solubility of water"? As the operating principle is different, the magnetic treatment studies are not relevant here and to be absolutely sure it would be necessary to perform a controlled experiment, but from the external similarities I would most likely expect it to be the same, and having no effect at all.

From their how it works:

The electronic unit works by sending out a signal which changes the electrical and physical properties of scale forming calcium molecules.

This action stops any further build-up of scale by preventing molecules from adhering to themselves or any other surface.

The solubility of the water is also increased, therefore existing scale is dissolved back into the water and gradually reduced.

And more "scientific" section (emphasis mine):

The nuclei upon which the crystals start growing are minute in size and have charged surfaces in their natural condition within the water. When they pass through the field, these naturally charged nuclei encounter considerable forces as the field interacts with them. The field acts at the surfaces of the nuclei and modifies the nature of the electrical charges and this ionisation effect thus alters the growth rate and pattern of the crystals in general and on specific planes.


That's interesting. I know of electrical devices that do this with corrosive effects using the galvanic reaction. I don't see what the mechanism would be for mineral accretion (which is what I'm assuming you're talking about).

My knowledge of the subject suggests to me that mineral deposits (like calcium) won't be bothered by any sort of electrical system (usually those are dealt with by installing a water conditioner to soften the water, or by putting mild acid (e.g. vinegar) into the pipes). I also know that, without a secondary reactive metal, the galvanic thing won't work.


Yea, I looked at the link you provided, and I agree. The "How it Works" section is particularly hilarious. It claims that the device increases the solubility of water, which cannot be increased without increasing the temperature, pressure, or reducing the mineral load in the solution...All of which are pretty much impossible for this product.


Examining their FAQ, I see two claims:

  • That "As the scale does not stick to pipework and appliances it all goes down the plug and leaves the house with the water."

  • That when it is working you should see a "Reduction in use of soap, soap powder, shampoo, detergents and cleaners."

The first claim would suggest that the calcium remains dissolved in the water as it leaves the tap - i.e. that there is (slightly) more calcium in the water you wash with.

The second claim would suggest that the water is less "hard", and the soaps don't need to overcome the calcium dissolved in the water - i.e. that there is significantly less calcium in the water you wash with.

Independent of the mechanism the device uses, these claims are self-inconsistent.

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