Water hardness in Diest
14 °fH hard
Tap water in Diest is hard: 14 °fH (140 mg/L · 8.2 gpg · 7.9 °dH).
Source: VMM, Kwaliteit van het drinkwater per leveringsgebied 2024, bijlage 2 (mediane concentratie) (2024) · data checked 2026-10-19
Range across supply zones: 87–177 mg/L.
De Watergroep supplies this part of Flanders with a mix of groundwater and canal-fed surface water, so hardness sits between the soft sandy Campine and the hard chalk areas. The 2024 figure is 140.4 mg/L CaCO₃, within a reported range of 87.3 to 176.7 mg/L, so the exact value depends on your street. At this level scale forms steadily in kettles, shower heads and boilers, so regular descaling is advisable and a softener can be worth considering.
Belgian suppliers report hardness in °f (French degrees); 1 °f = 10 mg/L CaCO₃.
Water data
| Total hardness | 14 °fH |
|---|---|
| Utility | De Watergroep |
How Diest compares
- Tap water in Diest is 56 % softer than the median of the 1091 cities we track in Belgium (31.6 °fH).
- By hardness it ranks 930 of 1091 in Belgium (1 = hardest); 15 % of these cities have softer water.
- In Vlaams-Brabant it is number 59 of 59 cities; the regional median is 26.6 °fH.
- Nearest city with clearly softer water: Meerhout, 16 km away (6.8 °fH).
- Nearest city with clearly harder water: Kortenaken, 9 km away (18.4 °fH).
Ranking of the hardest and softest water in Belgium →
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 Diest
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| 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 Diest water hard or soft?
It is hard: 140 mg/L as CaCO₃ (8.2 gpg, 7.9 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Diest 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 Diest water?
8.2 gpg, equal to 7.9 °dH, 14 °fH or 140 mg/L calcium carbonate.
What dishwasher salt setting should I use in Diest?
For 140 mg/L (7.9 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Diest?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: VMM, Kwaliteit van het drinkwater per leveringsgebied 2024, bijlage 2 (mediane concentratie) (2024). Method: figure published by the water supplier. VMM, Kwaliteit van het drinkwater per leveringsgebied 2024, bijlage 2 (mediane concentratie) · Outdated figure? Tell us