Water hardness in Grez-Doiceau
39.4 °fH very hard
Tap water in Grez-Doiceau is very hard: 39.4 °fH (394 mg/L · 23 gpg · 22 °dH).
Source: SPW, qualité de l'eau potable par zone de distribution, année civile 2025 (2025) · data checked 2026-10-19
Range across supply zones: 370–417 mg/L.
Grez-Doiceau (Walloon Brabant) is supplied by SWDE. The SPW gives a 2025 median of 394 mg/L CaCO₃, between 370 and 417 mg/L: very hard, among the highest values in this batch. The range is narrow. A softener is worth considering if you want to limit scale.
Belgian suppliers report hardness in °f (French degrees); 1 °f = 10 mg/L CaCO₃.
Water data
| Total hardness | 39.4 °fH |
|---|---|
| Utility | SWDE |
How Grez-Doiceau compares
- Tap water in Grez-Doiceau is 25 % harder than the median of the 1091 cities we track in Belgium (31.6 °fH).
- By hardness it ranks 219 of 1091 in Belgium (1 = hardest); 80 % of these cities have softer water.
- In Brabant wallon it is number 25 of 82 cities; the regional median is 36.6 °fH.
- Nearest city with clearly softer water: Bierbeek, 11 km away (17.9 °fH).
- Nearest city with clearly harder water: Virginal-Samme, 36 km away (50.2 °fH).
Ranking of the hardest and softest water in Belgium →
What it means at home
- Severe scale: heater elements and washing-machine heaters fail early.
- Detergent use is very high; taps and screens coat within days.
- Dishwasher at maximum salt setting.
- An ion-exchange softener is practically essential; RO for drinking water.
How much salt will you use for softening?
Yes. At this hardness a softener pays for itself through appliance life and detergent.
Descale a coffee machine or kettle about every 1 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Grez-Doiceau
| Brand | Setting for this water |
|---|---|
| Bosch | H06 |
| Miele | 22 °dH |
| AEG / Electrolux | 5 |
| Beko | 6th |
| Hoover | S3 |
| LG | H4 |
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 Grez-Doiceau water hard or soft?
It is very hard: 394 mg/L as CaCO₃ (23 gpg, 22 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Grez-Doiceau safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Belgian suppliers report hardness in °f (French degrees); 1 °f = 10 mg/L CaCO₃.
How many grains per gallon is Grez-Doiceau water?
23 gpg, equal to 22 °dH, 39.4 °fH or 394 mg/L calcium carbonate.
What dishwasher salt setting should I use in Grez-Doiceau?
For 394 mg/L (22 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Grez-Doiceau?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: SPW, qualité de l'eau potable par zone de distribution, année civile 2025 (2025). Method: figure published by the water supplier. SPW, qualité de l'eau potable par zone de distribution, année civile 2025 · Outdated figure? Tell us