Water hardness in Gembloux
38.1 °fH very hard
Tap water in Gembloux is very hard: 38.1 °fH (381 mg/L · 22.2 gpg · 21.3 °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: 362–400 mg/L.
SWDE supplies this area mostly from groundwater held in limestone and chalk, while part of Walloon supply comes from surface water; water that has passed through lime-rich rock is naturally hard. The 2025 figure is 380.8 mg/L CaCO₃, within a reported range of 361.5 to 400.0 mg/L, so the exact value depends on your street. At this level limescale builds up quickly in kettles, boilers and washing machines, so descaling and a softener are worth considering.
Belgian suppliers report hardness in °f (French degrees); 1 °f = 10 mg/L CaCO₃.
Water data
| Total hardness | 38.1 °fH |
|---|---|
| Utility | SWDE |
How Gembloux compares
- Tap water in Gembloux is 21 % harder than the median of the 1091 cities we track in Belgium (31.6 °fH).
- By hardness it ranks 267 of 1091 in Belgium (1 = hardest); 75 % of these cities have softer water.
- In Namur it is number 15 of 137 cities; the regional median is 32.3 °fH.
- Nearest city with clearly softer water: Mornimont, 11 km away (30.4 °fH).
- Nearest city with clearly harder water: Oisquercq, 36 km away (48.9 °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 Gembloux
| Brand | Setting for this water |
|---|---|
| Bosch | H06 |
| Miele | 21 °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 Gembloux water hard or soft?
It is very hard: 381 mg/L as CaCO₃ (22.2 gpg, 21.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Gembloux 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 Gembloux water?
22.2 gpg, equal to 21.3 °dH, 38.1 °fH or 381 mg/L calcium carbonate.
What dishwasher salt setting should I use in Gembloux?
For 381 mg/L (21.3 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Gembloux?
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