Water hardness in Cairu
99 mg/L moderately hard
Tap water in Cairu is moderately hard: 99 mg/L (5.8 gpg · 5.5 °dH · 9.9 °fH).
Source: Ministério da Saúde, SISAGUA – controle semestral (Empresa Baiana De Aguas E Saneamento Sa), CC BY-ND 3.0 (2026) · data checked 2026-10-20
Range across supply zones: 45–175 mg/L.
Empresa Baiana De Aguas E Saneamento Sa supplies Cairu in Bahia. Reported hardness is 99.0 mg/L as CaCO₃, which is moderate, but samples range widely from 45.4 to 175.0 mg/L. The source is the Ministry of Health's SISAGUA data, 2026.
Portaria GM/MS nº 888/2021 sets a maximum of 300 mg/L CaCO₃ for total hardness (dureza total); operators report it in mg/L to SISAGUA.
Water data
| Total hardness | 99 mg/L |
|---|---|
| Utility | Empresa Baiana De Aguas E Saneamento Sa |
How Cairu compares
- Tap water in Cairu is 133 % harder than the median of the 1915 cities we track in Brazil (43 mg/L).
- By hardness it ranks 211 of 1915 in Brazil (1 = hardest); 89 % of these cities have softer water.
- In Bahia it is number 36 of 148 cities; the regional median is 66 mg/L.
- Nearest city with clearly softer water: Camamu, 50 km away (17 mg/L).
- Nearest city with clearly harder water: Laje, 54 km away (135 mg/L).
Ranking of the hardest and softest water in Brazil →
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 Cairu
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 6 °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 Cairu water hard or soft?
It is moderately hard: 99 mg/L as CaCO₃ (5.8 gpg, 5.5 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Cairu safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Portaria GM/MS nº 888/2021 sets a maximum of 300 mg/L CaCO₃ for total hardness (dureza total); operators report it in mg/L to SISAGUA.
How many grains per gallon is Cairu water?
5.8 gpg, equal to 5.5 °dH, 9.9 °fH or 99 mg/L calcium carbonate.
What dishwasher salt setting should I use in Cairu?
For 99 mg/L (5.5 °dH) check your manufacturer's table: level 2–3.
Do I need a water softener in Cairu?
Not essential; a scale inhibitor protects the heater cheaply.
Source
Source: Ministério da Saúde, SISAGUA – controle semestral (Empresa Baiana De Aguas E Saneamento Sa), CC BY-ND 3.0 (2026). Method: figure published by the water supplier. Ministério da Saúde, SISAGUA – controle semestral (Empresa Baiana De Aguas E Saneamento Sa), CC BY-ND 3.0 · Outdated figure? Tell us