Tap water hardness in Zuid-Holland
We have published hardness data for 5 cities in Zuid-Holland. The median is 8 °dH; the hardest water is in Katwijk aan Zee (8.4 °dH), the softest in Rotterdam (7.6 °dH).
100 % 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 Zuid-Holland, hardest first
| °dH | mg/L | ||
|---|---|---|---|
| Katwijk aan Zee | 8.4 | 149 | hard |
| Scheveningen | 8.1 | 144 | hard |
| Monster | 8 | 143 | hard |
| Naaldwijk | 7.8 | 139 | hard |
| Rotterdam | 7.6 | 136 | hard |