Water hardness in Mairinque
234 mg/L very hard
Tap water in Mairinque is very hard: 234 mg/L (13.7 gpg · 13.1 °dH · 23.4 °fH).
Source: Ministério da Saúde, SISAGUA – controle semestral (Saneaqua Mairinque S A), CC BY-ND 3.0 (2026) · data checked 2026-10-20
Range across supply zones: 27–139000 mg/L.
Mairinque, in São Paulo state, is served by Saneaqua Mairinque S.A. The 2026 SISAGUA median is 234.0 mg/L as CaCO₃, which is very hard. The reported range runs from 26.5 to 139000.0 mg/L, and the upper value is implausible, most likely a data entry error. Treat the median with caution and ask the utility for a current analysis. If the median is accurate, scale on heaters and appliances would be significant.
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 | 234 mg/L |
|---|---|
| Utility | Saneaqua Mairinque S A |
How Mairinque compares
- Tap water in Mairinque is 451 % harder than the median of the 1915 cities we track in Brazil (43 mg/L).
- By hardness it ranks 17 of 1915 in Brazil (1 = hardest); 99 % of these cities have softer water.
- In São Paulo it is number 1 of 530 cities; the regional median is 42 mg/L.
- Nearest city with clearly softer water: Alumínio, 5 km away (43 mg/L).
Ranking of the hardest and softest water in Brazil →
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 Mairinque
| Brand | Setting for this water |
|---|---|
| Bosch | H04 |
| Miele | 13 °dH |
| AEG / Electrolux | 3 |
| Beko | 4th |
| Hoover | S2 |
| 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 Mairinque water hard or soft?
It is very hard: 234 mg/L as CaCO₃ (13.7 gpg, 13.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Mairinque 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 Mairinque water?
13.7 gpg, equal to 13.1 °dH, 23.4 °fH or 234 mg/L calcium carbonate.
What dishwasher salt setting should I use in Mairinque?
For 234 mg/L (13.1 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Mairinque?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Ministério da Saúde, SISAGUA – controle semestral (Saneaqua Mairinque S A), CC BY-ND 3.0 (2026). Method: figure published by the water supplier. Ministério da Saúde, SISAGUA – controle semestral (Saneaqua Mairinque S A), CC BY-ND 3.0 · Outdated figure? Tell us