Water hardness in Cascais
90 mg/L moderately hard
Tap water in Cascais is moderately hard: 90 mg/L (5.2 gpg · 5 °dH · 8.9 °fH).
Source: Águas de Cascais - Controlo de qualidade da água de 2024 (Ca, Mg, dureza, K por zona) (2024) · data checked 2026-10-29
Range across supply zones: 60–119 mg/L.
Águas de Cascais publishes hardness by supply zone, and Cascais town sits in Zona 6 of its 2024 control table: 60 to 119 mg/L CaCO₃. The 89.5 mg/L shown is the midpoint of that range, not a measured average. The utility's concelho-wide Q2 2026 report gives a wider 52 to 163 mg/L, because zones differ. Moderate hardness means a kettle or coffee machine needs descaling now and then.
Portuguese operators report "dureza total" in mg/L CaCO₃ to ERSAR.
Water data
| Total hardness | 90 mg/L |
|---|---|
| Utility | Águas de Cascais |
How Cascais compares
- Tap water in Cascais is 7 % harder than the median of the 77 cities we track in Portugal (83 mg/L).
- By hardness it ranks 32 of 77 in Portugal (1 = hardest); 57 % of these cities have softer water.
- In Lisboa it is number 3 of 13 cities; the regional median is 50 mg/L.
- Nearest city with clearly softer water: Oeiras, 10 km away (42 mg/L).
- Nearest city with clearly harder water: Alcabideche, 4 km away (289 mg/L).
Ranking of the hardest and softest water in Portugal →
What it means at home
- Visible kettle scale every few weeks; vinegar or citric acid is enough.
- Water heater and washing machine: some long-term scale; a scale inhibitor slows it.
- Dishwasher: medium salt setting.
- Softener optional; pays off mainly with a gas boiler or tankless heater.
How much salt will you use for softening?
Optional. A scale inhibitor or a small softener protects the heater; soap savings are modest.
Descale a coffee machine or kettle about every 3 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Cascais
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 5 °dH |
| AEG / Electrolux | 2 |
| Beko | 2nd |
| Hoover | S1 |
| LG | H1 |
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 Cascais water hard or soft?
It is moderately hard: 90 mg/L as CaCO₃ (5.2 gpg, 5 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Cascais safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Portuguese operators report "dureza total" in mg/L CaCO₃ to ERSAR.
How many grains per gallon is Cascais water?
5.2 gpg, equal to 5 °dH, 8.9 °fH or 90 mg/L calcium carbonate.
What dishwasher salt setting should I use in Cascais?
For 90 mg/L (5 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Cascais?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Águas de Cascais - Controlo de qualidade da água de 2024 (Ca, Mg, dureza, K por zona) (2024). Method: computed from supplier's calcium and magnesium. Águas de Cascais - Controlo de qualidade da água de 2024 (Ca, Mg, dureza, K por zona) · Outdated figure? Tell us