Do magnets remove limescale from water pipes?

Can you keep your pipes clean and clear by applying a magnetic field?
26 April 2009



I’ve been told a magnetic field can dissolve lime scale in water pipes. Is this true and how does it work since the pipes and I believe the lime scale aren’t ferrous and not affected by a magnet.


We put this to Dr Hugh Hunt, from Cambridge University's Engineering department...

I am Hugh Hunt from Cambridge University Engineering Department. Well, there are lots of manufacturer's websites that claim that if you put magnets on your water pipes then that prevents limescale build up on the element of your immersion heater.

Well it's obviously in the manufacturer's interest to make these claims, but let's suppose that, in the last year, a manufacturer has sold a thousand of these devices and they get one letter which says how fantastic it is, another ten letters that say that doesn't work. Well they can give ten refunds. They have still made quite a lot of money and they can publish that one nice letter.

That may be what we are seeing on the websites [selling these gadgets]; that's possibly being a bit mean, but I am a bit puzzled that there aren't any quoted refereed scientific publications out of the mainstream literature [supporting these claims].

Surely, if there was something really scientific going on here it would be well and truly understood. So I just wonder... Now there are few possible candidate theories all to do with magneto-hydrodynamics and water memory and things to do with nucleation and so on, you can read all about these. 

But where does that leave us? Well I think if you have found that one of these devices works for you, well it doesn't do any harm so you may as well carry on using it. But if you find that it doesn't work then perhaps there's no surprise in that.


Hi - there's two products being confused here. There's one type that simply wraps around your incoming water supply - seems unlikely to work to me. The second is one that's fitted into the central heating system pipework so the fluid that circulates within the central heating system passes through. This second type catches any iron/steel fragments from the rads/boiler so reducing wear on the central heating unit. There's a valve on each side of the unit that lets you (once a year or as needed) remove the mesh filter and wash out any fragments it's caught. Professional job to fit, easy to clean the filter.

So the article asks where scientific studies are, and the comments section gives us anecdotes, which is typical of anything that doesn't live up to manufacturer claims.

Want my anecdote too? We recently had a new boiler installed with a new magnetic pipe thing. Last week we bought a new kettle and it's already scaled. And our bathroom, tiles, taps are permanently covered in scale - its a losing battle. So, there's my anecdotal data.

My opinion? It's BS.

Sometime in the early 1990’s after being sick and tired of trying to get the lime or calcium deposits off my humidifier screens. I ran across a little magnetic device in the McMaster-Carr catalog. It cost $35. I bought it and installed it using a ¼” polypropylene line just before the heating season started. When the following spring arrived, I went to go about cleaning the dreaded humidifier system. Much to my surprise, when I started taking it apart, the lime or calcium build up was all soft and wet powdery pumice like material, that just rinsed off with water. That convinced me to go buy the $25 ones on Amazon to add them to my incoming water line. Since doing that, another thing I’ve noticed, is that I know longer need to clean around the drains of my sinks with CLR to remove the lime/calcium build-up. So, does this Magnetic Water Conditioner: 1 Soften the water? I doubt it. 2. Ionize the water? Not sure, maybe/maybe not. 3. Change the alkalinity. Don’t Know. What I do know is that it does work, and it does do some kind of water conditioning that continues to surprise the hell out of me. And I do know that the $25 Magnetic Conditioner is all you really need to condition the water. Oh, and I have no vested interest in any company that sells or manufactures these devices. I work for a high voltage equipment manufacturing firm in Chicago.

In 2004 I found that our two electric water heaters were bady affected by calcium on the heating elements and, on the smaller unit, over 50% of the internal space was cacium!
First thought was a water softener but this has ongoing costs so I took a chance on a UK system which produced a magnetic field round the fresh water inlet pipe. A small diameter cable is wound round the pipe for about a foot or so. The promise of the company was that if I still had calcium forming in any meaningful way ( hard, rather than soft deposit) the company would refund my money. I took the chance and 4 years later, when we sold the bed and breakfast property, there had been no further problem. I have since spoken to several people in the south of England-very hard water- and those who have gone for magnets, (not the same system as I had, just circular magnets) reported a clear improvement. Not serious scientific study but make of it as you will.

From Wikipedia, Limescale:
Iron components of limescale
Scale is often coloured because of the presence of iron-containing compounds. The three main iron compounds are wustite (FeO), hematite (Fe2O3), and magnetite (Fe3O4).
end of citation.
If limescale include iron components, these can be tilted using magnets, and these iron compounds will disintegrate limescale.
I have no experience in that and don't know the concentration of iron in limescale. Laboratory experiments can clear the question.

where can i obtain magnets from

My best answer is that for $25 you can buy a pipe magnet yourself and do a before and after trial. There's nothing for you to lose except that $25.

...that setting fire to a $50 bill would stop your pipes from scaling up, you'd still do it just to find out if they were right, despite obvious evidence to the contrary, and in the process encourage the charlatan to continue deceiving people?

The best solution, surely, is to read the answer above, which concludes that there is no scientific basis or evidence whatsoever for the claimed effect, and don't waste any money.

surely the trade descriptions act covers this ,if it doesnt work then the people selling them should be prosecuted .

I've posted one of the more interest links I came across while googling about these devices. It is a report of a test carried out on behalf of the US department of energy at a water treatment plant of a commercial magnetic scale inhibiting device.

This particular test showed no beneficial effect. They examined samples of the scale that formed using x-ray diffraction and established it was calcite with no evidence of the aragonite that the manufacturers of many of these devices claim is formed instead.



Googling the name of the product tested, finds a website promoting both magnetic water treatment and magnetic diesel fuel saver units.

Some background information:

There is some evidence that magnetic fields may interact with calcium, but from what i can understand from those, but not a physicist or chemist, is that it's effects are very minor.

These type of devices do usually have some basis in truth, but are usually exaggerated. So from my understanding of this is that these do have some type of effect, but it's so minor that it would take a chemist to detect the reduction...

Would love to hear a comment from someone that can fully understand documents i posted above.

Found this post when searching for the same info so thought i share it with others searching for this type of information.

Wouldn't any magnetic debris in the water just cling to the inside of the pipe until eventually clogging the whole thing? Or is the point of this that the magnets change the properties of the mineral and that somehow helps not clog stuff up? That seems like it would either be temporary and quickly return to normal after passing through the magnet or that it would be a mass produced virtually maintenance free product by now. Maybe Elon should make one and have another pipe dream for sale.

Nothing is removed from the water by magnets. But Argonite doesn’t build up like Calcite.
It can be wiped off of the inside of a glass bowl with your finger afte evaporating the water.
It doesn’t collect in a pipe. It passes on through...
And that’s the truth.

I`ve used magnets for some time and find that I have very little trouble like round taps and in kettles,
My son and especially his wife was having trouble with shower heads blocking up taps and kettles, I suggested using magnets now they are fine. I don`t need scientific evidence I have experience.

I bought one of these devices and fitted it to plastic pipe before the water entered a water ionizer, it did NOT work the ionizer blocked up with limescale in a very short time.
I would like to know would it work any better on copper pipe, can anyone answer?

...because they are peddling you snake oil. As the answer above indicates, there's no scientific reason for it to work, and it doesn't!

So save your money and invest in a water softener instead!

Magnets do NOT remove the hardness in mains water - calcium carbonate is still there and that's that! A magnetic field or electric current MAY alter the ions temporarily as the water passes through the device, but the effect is very quickly lost. If they really did work as claimed, then water softener companies would soon go out of business. Concerned about the truth? Time to get real!

Yes when water pass through the magnetic, lime scales are removed, water ph value is better, helps to get the sewage treatment process fast by 50%.
Neither I m a supplier or a manufacture r , but an engineer who have did research for personal interest , I have tasted raw water and water passed through the magnwtic-- ans. It's taste better.
2. Germs do not originate.
I filled 2 drums one with sewage water directly, and other through the magnetic.
After 1 day I sent for cod and bod testing, and one with magnet passed the IS test.
After 7 days you can't stand near the drum , but you can easily stand near the drum where sewage wS passed through magnet.

If you can provide me with robust, reproducible data demonstrating that, in a blind trial, these devices achieve what you allege then I'll believe you. Somehow I doubt you'll be able to produce such data, because they don't exist...

Pitiful answer. No definate yes or no. Do you just not know, yourself? If so, say so. At least its an honest answer.

I don't think he's provided a pitiful answer; what he has highlighted is the lack of any published evidence to support the claims made by the people who make these devices that they are actually effective. A lack of evidence that they are not effective is not evidence that they are effective. Rather than speculate, he is expressing scepticism and urging people to think scientifically.

Your answer amounted to "well if it works, it works, and if it doesn't then too bad." You didn't answer the question at all. You could have at least provided a brief explanation of magneto-hydrodynamics or how magnetism affects calcium or nucleation. Perhaps even how strong magnetic fields may or may not affect non-ferrous materials like lime deposits.

Maybe the ones who say magnets don't work is they dont have enough calcium in their water to make a difference or maybe they are thinking the water will feel slippery. It doesn't! But I had my magnets on the pipes and then I had to get a new well. I thought I probably wouldn't need the magnets anymore and took them off! BIG mistake! I ruined a kitchen faucet and filled my other faucets with calcium deposits very quickly! So I put the magnets back on and saved my faucets from ruination. The way to clean a faucet is however, a job. They must be taken apart and cleaned with vinegar. Water will dissolve calcium but vinegar does a quicker job. After soaking the item for maybe half an hour and using a brush, all the calcium can be cleaned off. I also put a couple of tlbs of vinegar in my stool tanks about every 5 flushes. It keeps the works cleaner even with magnets on the line. It will also keep the stool itself free filling up with calcium and prevents backups.

We have galvanized pipes and hard water. We have rust in the pipes and I've heard that the magnets will clear out the rust. It's worth a shot to keep from having to replace all the pipes with pvc or copper. Thanks for any info on using magnets.

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