Tap water hardness in North Holland
We have published hardness data for 13 cities in North Holland. The median is 7.9 °dH; the hardest water is in Hoofddorp (8 °dH), the softest in Oud-Loosdrecht (6.3 °dH).
92 % of these cities have hard or very hard water (over 120 mg/L).
Dutch suppliers report °dH; most networks are softened centrally to 5.6–8.4 °dH.
Cities in North Holland, hardest first
| °dH | mg/L | ||
|---|---|---|---|
| Hoofddorp | 8 | 143 | hard |
| Alkmaar | 7.9 | 141 | hard |
| Den Helder | 7.9 | 141 | hard |
| Haarlem | 7.9 | 141 | hard |
| Hoorn | 7.9 | 141 | hard |
| Velsen-Zuid | 7.9 | 141 | hard |
| Zaandam | 7.9 | 141 | hard |
| Zaanstad | 7.9 | 141 | hard |
| Amstelveen | 7.8 | 139 | hard |
| Nieuw-Loosdrecht | 7.6 | 135 | hard |
| Hilversum | 7.2 | 129 | hard |
| Loosdrecht | 7.1 | 127 | hard |
| Oud-Loosdrecht | 6.3 | 112 | moderately hard |