Dutch tap water is safe everywhere, but it isn't equally hard everywhere. In one home the shower screen stays clean for weeks; in another you see white spots after just a few days. The difference is water hardness: the amount of limescale in your water. In this guide you'll find out how hard the water is in your province, how to check it by postcode and what you can do about it.
What is water hardness?
Water hardness shows how much calcium and magnesium your water contains. In the Netherlands it's measured in German degrees of hardness (°dH) or in millimoles per litre (mmol/l). 1 mmol/l equals 5.6 °dH.
Water companies use this scale:
| Hardness (°dH) | Category |
|---|---|
| 0 – 4 | Very soft |
| 4 – 8 | Soft |
| 8 – 12 | Medium |
| 12 – 18 | Fairly hard |
| 18 – 30 | Hard |
Water hardness by province
Most Dutch drinking water companies soften hard water centrally during treatment. As a result, Dutch tap water is soft on average: around 1.4 mmol/l according to the drinking water sector, about 8 °dH. Removing all the lime isn't allowed. If a water company softens its water, at least 1 mmol/l (5.6 °dH) must remain, because water that's too soft damages pipes.
This is what it looks like per province:
| Province | Average (°dH) | Category | Main water company |
|---|---|---|---|
| Groningen | 10.1 | Medium | Waterbedrijf Groningen |
| Zeeland | 9.5 | Medium | Evides |
| Limburg | 8.4 | Medium | WML |
| Noord-Holland | 7.9 | Soft | PWN, Waternet |
| Zuid-Holland | 7.9 | Soft | Dunea, Evides, Oasen |
| Noord-Brabant | 7.8 | Soft | Brabant Water |
| Fryslân | 7.7 | Soft | Vitens |
| Overijssel | 7.7 | Soft | Vitens |
| Utrecht | 6.8 | Soft | Vitens |
| Drenthe | 6.6 | Soft | WMD |
| Flevoland | 6.5 | Soft | Vitens |
| Gelderland | 6.3 | Soft | Vitens |
These are averages. Within a province, hardness varies by municipality and sometimes by street. In the province of Groningen, for example, it ranges from 6 to 12.5 °dH. Want to know exactly? Then check your own postcode.
How do you check water hardness by postcode?
- Find your water company. The company that supplies your water is shown on your water bill.
- Enter your postcode or town. Most water companies, such as WMD, WML and Brabant Water, have a water hardness lookup on their website.
- Or measure it yourself. Test strips show how hard your water is within a minute. They often come with a new dishwasher or can be bought separately.
How do you notice hard water in the shower?
- Limescale in your shower head. Blocked spray holes give a weaker, uneven stream.
- White spots on your shower screen, tiles and taps.
- Less lather. Soap and shampoo lather less, so you use more of them.
- Skin and hair. Many people find their skin feels drier after showering and their hair looks duller.
Limescale builds up even with soft water, especially when the water is hot. That's why almost every shower head is affected after a while.
Good to know: hard water isn't bad for your health. There's no evidence that it's harmful, which is why the WHO and the EU don't set a health limit for it. It's about comfort and maintenance.
What can you do about it?
Descale your shower head regularly. A soak in vinegar or citric acid keeps the spray holes open. Read how in removing limescale from your shower head.
Squeegee your shower screen. A 30-second wipe after showering prevents most limescale spots.
A shower head with a filter does not soften your water. A filter holds back loose particles from the pipes and breaks down free chlorine, but dissolved limescale passes straight through. A filter mainly makes sense where tap water is chlorinated, as in Belgium, France and Spain. Not sure? First read shower filter: worth it or not? or take a look at the Besjaar Shower Head with Filter.
Really hard water at home? Then a central water softener is the thorough solution. It costs more and is usually installed by a plumber.
Frequently asked questions
How do I check my water hardness by postcode?
Check your water bill to see which company supplies your water, then enter your postcode or town on their website. You can also measure it yourself with test strips.
Is hard water bad for your health?
No. There's no evidence that hard water is harmful. It mainly causes limescale and can make your skin and hair feel drier.
How hard is the water in Drenthe?
Soft to medium. WMD softens the water where needed to about 8 °dH. The average in the province is around 6.6 °dH.
Besjaar makes shower heads and filters for Dutch bathrooms, from Assen. Better water, every day.