Water hardness in Katwijk aan Zee
8.4 °dH hard
Tap water in Katwijk aan Zee is hard: 8.4 °dH (149 mg/L · 8.7 gpg · 14.9 °fH).
Source: Dunea drinkwater Katwijk wettelijk 2025 jaarrapport (2025) · data checked 2026-11-06
Range across supply zones: 128–196 mg/L.
Dutch suppliers report °dH; most networks are softened centrally to 5.6–8.4 °dH.
Water data
| Total hardness | 8.4 °dH |
|---|---|
| Utility | Dunea |
How Katwijk aan Zee compares
- Tap water in Katwijk aan Zee is 11 % harder than the median of the 654 cities we track in the Netherlands (7.5 °dH).
- By hardness it ranks 102 of 654 in the Netherlands (1 = hardest); 85 % of these cities have softer water.
- In Zuid-Holland it is number 1 of 5 cities; the regional median is 8 °dH.
- Nearest city with clearly softer water: Breukelen, 40 km away (6.5 °dH).
- Nearest city with clearly harder water: Werkendam, 54 km away (10.6 °dH).
Ranking of the hardest and softest water in the Netherlands →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Katwijk aan Zee
| Brand | Setting for this water |
|---|---|
| Bosch | H02 |
| Miele | 8 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| Hoover | S1 |
| LG | H2 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Katwijk aan Zee water hard or soft?
It is hard: 149 mg/L as CaCO₃ (8.7 gpg, 8.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Katwijk aan Zee safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Dutch suppliers report °dH; most networks are softened centrally to 5.6–8.4 °dH.
How many grains per gallon is Katwijk aan Zee water?
8.7 gpg, equal to 8.4 °dH, 14.9 °fH or 149 mg/L calcium carbonate.
What dishwasher salt setting should I use in Katwijk aan Zee?
For 149 mg/L (8.4 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Katwijk aan Zee?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: Dunea drinkwater Katwijk wettelijk 2025 jaarrapport (2025). Method: figure published by the water supplier. Dunea drinkwater Katwijk wettelijk 2025 jaarrapport · Outdated figure? Tell us