Water hardness in Hermosillo
204 mg/L very hard
Tap water in Hermosillo is very hard: 204 mg/L (11.9 gpg · 11.4 °dH · 20.4 °fH).
Source: Agua de Hermosillo - Resultados de análisis fisicoquímico del agua potable suministrada, enero 2024 (2024) · data checked 2026-10-23
Range across supply zones: 120–257 mg/L.
9 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| mg/L | mg/L | ||
|---|---|---|---|
| Zona Centro H. Flor (Hacienda de la Flor) | 212 | 212 | very hard |
| Zona Norponiente Bagotes | 220 | 220 | very hard |
| Zona Norponiente Pueblitos (Captación Pueblitos) | 214 | 214 | very hard |
| Zona Norte Alto (Captación Victoria, Palermo) | 166 | 166 | hard |
| Zona Norte Bajo (Pila Periférico) | 257 | 257 | very hard |
| Zona Parque Industrial (Pozo 1) | 204 | 204 | very hard |
| Zona Sur (Acueducto Independencia, Planta Potabilizadora Sur) | 120 | 120 | hard |
| Zona Suroriente Willard (Gola) | 136 | 136 | hard |
| Zona Surponiente Bagotes Sur (Corceles) | 202 | 202 | very hard |
Hermosillo is served by a municipal utility in a region where supply combines reservoirs and groundwater. The figure shown, 204.0 mg/L CaCO₃, is the median across 9 supply zones, which range from 120.0 to 257.0 mg/L, so it depends on which zone your street is in. Limescale builds quickly in kettles, boilers and washing machines, so frequent descaling or a softener is worth considering.
Mexico's NOM-127-SSA1-2021 sets a 500 mg/L CaCO₃ limit for total hardness in drinking water.
Water data
| Total hardness | 204 mg/L |
|---|---|
| Utility | Agua de Hermosillo |
How Hermosillo compares
- Tap water in Hermosillo is 30 % softer than the median of the 9 cities we track in Mexico (292 mg/L).
- By hardness it ranks 8 of 9 in Mexico (1 = hardest); 13 % of these cities have softer water.
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 Hermosillo
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 11 °dH |
| AEG / Electrolux | 3 |
| Beko | 3rd |
| 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 Hermosillo water hard or soft?
It is very hard: 204 mg/L as CaCO₃ (11.9 gpg, 11.4 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Hermosillo safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. Mexico's NOM-127-SSA1-2021 sets a 500 mg/L CaCO₃ limit for total hardness in drinking water.
How many grains per gallon is Hermosillo water?
11.9 gpg, equal to 11.4 °dH, 20.4 °fH or 204 mg/L calcium carbonate.
What dishwasher salt setting should I use in Hermosillo?
For 204 mg/L (11.4 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Hermosillo?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: Agua de Hermosillo - Resultados de análisis fisicoquímico del agua potable suministrada, enero 2024 (2024). Method: figure published by the water supplier. Agua de Hermosillo - Resultados de análisis fisicoquímico del agua potable suministrada, enero 2024 · Outdated figure? Tell us