Last updated: August 16, 2026
Hard water leaves calcium and magnesium behind on your hair and on your styling tools. These minerals conduct heat differently than hair keratin, which means the heat from a hairdryer or curling attachment may spread less evenly. Limescale can also bake onto a hot ceramic surface and damage that surface over time.
In short
- Hard water contains a lot of calcium and magnesium. These minerals attach to your hair shaft and can also bake onto the coating of a hot styler.
- Water hardness in the Netherlands is measured in °dH. The national average is around 8 °dH, with softer water in Friesland and Flevoland and harder water in parts of Limburg, Overijssel and Zeeland.
- Mineral deposits conduct heat differently than hair keratin, which makes local differences in heat absorption during styling plausible. This specific effect has not, however, been separately studied for heat styling.
- Limescale that bakes onto a hot plate can damage a styling tool's coating over time, especially with a thin coating.
- A filter showerhead, vinegar rinse or chelating shampoo reduce mineral buildup, but no single solution removes hard water completely.
Below you'll find out exactly how hard water is measured in your region, what it does to your hair and your styling tools, and which approach keeps it under control best in practice.
What is hard water, and how hard is the water in the Netherlands?
Hard water is tap water with a high calcium and magnesium content. In the Netherlands this is expressed in German hardness degrees (°dH), and this value varies considerably by region.
One degree of German hardness equals 10 milligrams of calcium oxide per liter of water. The higher the number, the harder (more lime-rich) the water. Water companies in the Netherlands generally use this classification:
- Very soft: below 3 °dH
- Soft: 3 to 6 °dH
- Moderately hard: 6 to 9 °dH
- Hard: 9 to 12 °dH
- Very hard: above 12 °dH
The national average is around 8 °dH, so right on the border between soft and moderately hard. That average, however, says little about your own tap. The Netherlands has ten regional drinking water companies, and hardness varies by water extraction area. Roughly speaking, the water in Friesland, Flevoland and Drenthe is softest (around 6 to 8 °dH), while parts of Limburg, Overijssel, Zeeland and Groningen have considerably harder water, sometimes reaching as high as 12 to 15 °dH.
These figures are regional averages from multiple sources that vary slightly from one another. For the exact value at your home, it's best to enter your postcode on your own drinking water company's website.
What does hard water do to your hair, aside from styling?
Calcium and magnesium from hard water attach to your hair shaft. That's not a myth: this uptake of minerals into hair has actually been measured in research.
In a published study (Evans, Marsh & Wickett, Journal of Cosmetic Science, 2011), a laboratory technique was used to measure how much calcium and magnesium human hair absorbs from water of varying hardness. How much attaches depends, among other things, on how damaged the hair already is and how hard and how acidic the water is. Damaged hair (for example from bleaching or previous heat damage) generally binds more minerals, simply because there are more attachment points on the hair shaft.
The effects of this mineral buildup are described almost identically by virtually every major hair brand: Kérastase, Living Proof, Davines, L'Oréal and Malibu C all mention it. The deposit lays a thin layer over the outside of your hair, making the cuticle (the protective layer) feel rougher, allowing moisture and conditioner to penetrate less well, and leaving hair feeling dull, rough and sometimes brittle. That description is strikingly consistent across brands, which fits logically with the underlying research. But it's also largely the same explanation recurring everywhere in similar wording. So treat it as widely accepted and plausible, not as a fact independently confirmed ten times over.
Can limescale cause heat to spread unevenly over your hair?
That's physically plausible, but hasn't been separately researched yet. Mineral deposits conduct heat differently than hair keratin itself, so an uneven layer of minerals could in theory lead to local differences in heat absorption, also known as hotspots.
This is the part you won't find fully explained anywhere, so let's be precise about what we do and don't know.
What we do know: hair absorbs minerals from hard water (see above), and this uptake isn't uniform. Some spots on the hair shaft bind more calcium and magnesium than others, depending on local damage and porosity. Materials research into limescale (calcium carbonate) also shows that this type of deposit generally conducts heat better than keratin-containing material: the thermal conductivity (how quickly something transfers heat, expressed in W/(m·K)) of calcium carbonate deposits ranges, depending on the density of the layer, roughly between 0.4 and 2.7 W/(m·K), compared to around 0.03 to 0.04 W/(m·K) for the keratin-containing materials studied. That's a considerable difference.
What we don't know: as far as can be found, there is no study that has specifically measured, for hair during styling, whether an uneven mineral layer actually causes measurable hotspots while blow-drying or styling with a curling attachment. It's a logical, physically grounded assumption based on existing materials data, not a proven cause-and-effect relationship specific to heat styling. So think of it as "may contribute to uneven heat absorption", not as "causes proven hotspots".
In practice, you might notice this as hair that feels drier, stiffer or more damaged in some spots after styling, even though you used the same temperature and the same tool everywhere.
Can limescale also damage your curling attachment or hairdryer itself?
Yes, and that's the side almost nobody discusses. Minerals from hard water can bake onto a hot surface and damage a styling tool's coating over time.
Even heat tool manufacturers mostly mention this only in passing. Cloud Nine, a well-known straightener brand, states in its own care instructions that built-up product residue combined with the heat of the plates can have a corrosive effect, causing the coating to wear over time. Limescale isn't mentioned separately, but the same combination of heat and buildup logically applies just as much to mineral deposits from hard water. Cloud Nine recommends regularly removing buildup with a cloth and a solution of vinegar, baking soda or rubbing alcohol, and never with anything abrasive, since that causes scratches in the coating.
The logic behind this is fairly simple: limescale (calcium carbonate) bakes onto a hot surface, just like in a kettle. With a curling attachment or straightener, the repeated combination of heat, minerals and sometimes abrasive cleaning is added on top of that. With a thin spray coating, there's little material between that buildup and the core of the plate, which means the coating can visibly wear faster over time: less even glide, spots that work less well, hair that keeps snagging.
As far as can be found, this mechanism is broadly supported by general materials science and confirmed by at least one tool manufacturer itself. However, no independent lifespan test has been found that precisely measures how much faster a thin coating wears compared to a thicker, fully ceramic layer. So it's a plausible and partly confirmed mechanism, not an exactly quantified fact.
How do you recognize whether hard water is affecting your hair or your styling tool?
In your hair: dullness and stiffness soon after washing, shampoo that lathers poorly, color that fades faster, and product that "stays put" even after thorough rinsing. On your tool: a white-gray haze on the plates, hair that snags or squeaks more often during styling, and less smooth glide than when the tool was new.
Do you recognize both, and do you live in a region with a higher °dH value? Then there's a good chance hard water is playing a role.
What practically works against hard water damage to your hair?
There's no single solution that removes hard water completely. The most commonly recommended approach combines a filter (preventive) with a periodic treatment that removes existing buildup (curative).
| Approach | What it does | How often | What it doesn't do |
|---|---|---|---|
| Filter showerhead | Reduces the amount of minerals that reach your hair, before the water hits your head | Continuous, ongoing use | Doesn't remove minerals already stuck in your hair; works preventively, not curatively |
| Vinegar rinse | Diluted apple cider vinegar partly dissolves existing limescale buildup on your hair, as a final rinse after washing | 1x every 1 to 2 weeks | Can leave hair feeling dry if used too often; smells temporarily of vinegar |
| Chelating shampoo | Binds specifically to calcium and magnesium ions and rinses them away, more targeted than a regular clarifying shampoo | 1x every 1 to 2 weeks | Can be drying if used too often; not suitable as a daily shampoo |
| Water softener (whole house) | Treats the water at the source, so water from all taps is structurally less hard | One-time installation, lasting effect | Bigger investment; not an option if you rent or don't have space for an installation |
How do you prevent limescale from damaging your curling attachment or hairdryer?
Regularly wiping down the plates and removing limescale in time prevents it from baking in and damaging the coating. In a hard water region, this is just a bit more important than elsewhere.
- Let the tool cool down completely and unplug it before you start cleaning.
- Wipe the plates down after use with a slightly damp, soft cloth, especially if you live in a hard water region.
- Do you see a white haze? Use a cloth with a small amount of diluted vinegar or rubbing alcohol, never an abrasive sponge or anything sharp.
- Let the tool dry completely before you switch it on again or put it away.
- Do you live in a very hard water region and use the tool daily? Then a filter showerhead or softener is just as relevant for your tool as for your hair.
Frequently asked questions
Is using distilled water to wash my hair a solution for hard water?
In theory, yes, because distilled water contains virtually no minerals. For most people, however, it's not practical as a daily solution, due to the cost and hassle. A filter showerhead or chelating shampoo is a more realistic alternative for most households, with a comparable effect in the long run.
Should I clean my curling attachment or hairdryer more often if I live in a hard water region?
Yes, that's a reasonable precaution. Because minerals bake onto a hot surface faster in a hard water region, it helps to wipe the plates with a damp cloth more often and remove visible limescale haze sooner than if you lived in a soft water region.
Does setting a lower temperature help if I have hard water?
A lower temperature generally reduces heat damage, regardless of water hardness, so it's always a good idea if your results allow for it. It doesn't resolve the underlying mineral buildup in your hair itself. For that you need a separate approach, such as a chelating shampoo or vinegar rinse.
Does a whole-house water softener work better than a filter showerhead?
A whole-house softener structurally treats the water at the source for all taps, while a filter showerhead only changes the water at your shower and reduces hardness rather than removing it completely. A softener is a bigger investment but more thorough; a filter showerhead is cheaper and easier to install, especially in a rented home.
How often should I use chelating shampoo?
The most common recommendation is once every one to two weeks, not more often. Chelating shampoo cleans quite thoroughly and can dry out hair if used too often. In between, just use your regular shampoo and conditioner.
Can you tell from your hair or styling tool whether hard water is really a problem for you?
Signs in your hair include dullness, roughness soon after washing and shampoo that lathers poorly. Signs on your tool include a white-gray haze on the plates and hair that snags more often during styling. If you recognize both, and you live in a region with a higher °dH value, there's a good chance hard water is playing a role.
Because limescale on a hot surface can damage a styling tool's coating over time, the thickness and quality of that coating matters, especially if you live in a hard water region. The Ace & Taylor curling attachment has a fully ceramic coating instead of a thin spray coating, which makes the tool more resistant to that kind of wear. In Ace & Taylor's own research (214 users, 30 days of use, not an independent study), 87% experienced immediately less hair damage.
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