Do magnetic and electronic water softeners work?

Part of our filters and softeners guide

A box or a pair of magnets on the pipe, no salt and a promise of less limescale. What do UK official sources say it does, and how can you check your own tap with a 20-in-1 test strip?

By Andrew Tomlinson, WaterKit · Last reviewed 29 October 2026

How is a magnetic water softener meant to work?

It is meant to change how limescale forms, not to soften the water. The Drinking Water Inspectorate says some devices are sold on the basis that a magnetic field changes scale crystals from needle-like to rhomboid, so they stick less to boiler heating elements, and that these devices do not soften the water. An ion-exchange softener swaps calcium and magnesium for sodium (see how a water softener works). The DWI says that where water is softened this way, it is important to keep an unsoftened outlet for drinking.

Do magnetic water softeners work?

Not as softeners, and both bodies are cautious about the scale claim too. The DWI says the science is based on continuous water flow and that the devices were designed for large industrial systems, not homes, where water may not flow for up to eight hours in 24.

The ASA's advice to advertisers comes from the Committee of Advertising Practice (CAP) executive, is dated 23 April 2025 and is not binding. It says the ASA and CAP understand that magnetic or electromagnetic conditioners cannot soften water. In 2007 the ASA upheld complaints about an advert saying a conditioner would stop limescale building up, judging after expert advice that the device could not prevent build-up in a single-pass domestic system. It adds that it understands there is no universally accepted theory of how the devices work and no evidence that they inhibit scale formation generally.

Do electronic water softeners work any differently?

In the sources we read, neither the DWI nor the ASA names "electronic" devices. The ASA's advice covers magnetic and electromagnetic conditioners, the closest official comment, and the same caution applies.

What one reader found

A 2010 thread on a money-saving forum asked whether clip-on magnets for limescale were worth buying. One member said they had been sent hard water magnets as a free gift with an order, had tried £1-shop magnets on the pipes, and even toy magnets, and found none of them had any effect, calling the free ones "Completely useless." It is one person's account from years ago, not a trial. Shared on MoneySavingExpert Forum.

Why might your own tap not match the area's hardness figure?

The area figure is an average. The DWI says its map shows typical hardness in England and Wales, that some areas have local variation the map does not show, and that for an accurate measurement you should ask your water company (see checking hardness by postcode).

The DWI classes water of 200 to 300 mg/l as calcium carbonate as hard and above 300 as very hard, and says hard water scales hot water systems, kettles and appliances. See also why your kettle gets limescale.

“The area figure is only an average, so I would never assume it describes what comes out of your own tap, especially if you are thinking of paying for a device on the strength of it. Read your own hardness first, then judge any claim against that.”

What should you ask before fitting one?

Ask for home-setting performance data and sale or return terms. The DWI recommends buying such a device only on a sale or return basis and requesting data on performance in the home. CAP says a seller without convincing trials should not state or imply that the product works, and that claims should note that results vary. For methods that do lower hardness, see softening hard water at home and whether you need a filter or a softener.

How can you check your own water before you decide?

Read your tap's hardness first, then judge any device against it. The WaterKit Water Test Kit hardness pad has colour steps at 0, 25, 50, 100, 250 and 425 mg/l. Fill a clean glass or cup with the water, dip one strip, wait 30 to 60 seconds and match the pad to the chart, or enter the colours in the free results checker (our hardness testing guide has the detail). Three limits apply. Whether the steps are calcium carbonate is unconfirmed, so the comparison below is our reading of the chart. Scale forms when water is heated, which a cold dip cannot show (see our limescale guide). A strip result is not a legal sample.

• A step of 250 or 425 would sit above the 200 mg/l level that the DWI, citing World Health Organisation guidelines, says will produce scale. A step of 100 or below would sit in its "soft" band.
• Because the DWI says these devices do not soften water, we would expect the same step before and after fitting one. A match would not show whether the device affects scale.

The area figure is an average, and the DWI says some areas have local variation its map does not show, so your own tap may differ. The hardness pad is the one that matters here, and a lower step after fitting a device would indicate that the hardness of the water itself had changed. Best pack: 20 strips, enough to read your hardness before a change and several times after, £5.99 (or £10.99 with a bacteria test), with free 2nd Class delivery on every order. See the kit

Your magnetic and electronic water softener questions

Does magnetic water softener work?

Not as a softener, says the DWI.

Magnetic water softener how does it work?

The claim is that a magnetic field changes how scale crystals form. The DWI says the devices do not soften water.

Electronic water softener do they work?

Neither the DWI nor the ASA gives separate guidance on devices sold as electronic.

Sources

1. Drinking Water Inspectorate, Water Hardness / Hard Water (undated page; hardness bands, the WHO 200 mg/l scale figure it cites, what the devices claim, that they do not soften water, continuous flow and eight hours, sale or return, local variation; read 29 October 2026).
2. Advertising Standards Authority and Committee of Advertising Practice, Water treatment devices (advice dated 23 April 2025, not binding; magnetic or electromagnetic conditioners, the 2007 ruling, evidence, qualified claims, trials; read 29 October 2026).
3. MoneySavingExpert Forum, Limescale and magnets - are they worth buying? (thread posted 24 August 2010; one member's account, not a trial; read 29 October 2026).
4. WaterKit, Water Test Kit (20-in-1 strip, 30 to 60 second read, optional rapid coliform test read after 24 to 48 hours, 20 strips £5.99, free 2nd Class delivery on every order) and results portal. The comments on expected readings are WaterKit's own reading of the colour chart steps.

Contains public sector information licensed under the Open Government Licence v3.0.