Water hardness in Três Rios
24 mg/L soft
Tap water in Três Rios is soft: 24 mg/L (1.4 gpg · 1.3 °dH · 2.4 °fH).
Source: Ministério da Saúde, SISAGUA – controle semestral (Saaetri), CC BY-ND 3.0 (2026) · data checked 2026-10-20
Range across supply zones: 17–30 mg/L.
Três Rios is supplied by a municipal utility; the sources checked do not name its intake. Records for 2026 give a median of 23.9 mg/L CaCO₃, with individual results from 16.8 to 29.6 mg/L. Limescale is rarely a problem at this level, and descaling the kettle is seldom necessary.
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 | 24 mg/L |
|---|---|
| Utility | Saaetri |
How Três Rios compares
- Tap water in Três Rios is 44 % softer than the median of the 1915 cities we track in Brazil (43 mg/L).
- By hardness it ranks 1467 of 1915 in Brazil (1 = hardest); 23 % of these cities have softer water.
- In Rio de Janeiro it is number 12 of 44 cities; the regional median is 14 mg/L.
- Nearest city with clearly softer water: Teresópolis, 29 km away (12 mg/L).
- Nearest city with clearly harder water: Paraíba do Sul, 21 km away (74 mg/L).
Ranking of the hardest and softest water in Brazil →
What it means at home
- Little or no limescale in kettles, water heaters or washing machines.
- Soap lathers easily; water does not dry skin or hair.
- Dishwasher: salt setting at minimum or off.
- No softener needed; a jug filter only changes taste.
How much salt will you use for softening?
No. Water this soft does not need softening.
Descale a coffee machine or kettle about every 6 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Três Rios
| Brand | Setting for this water |
|---|---|
| Bosch | H00 |
| Miele | 1 °dH |
| AEG / Electrolux | 1 |
| Beko | 1st |
| Hoover | S0 |
| LG | H0 |
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 Três Rios water hard or soft?
It is soft: 24 mg/L as CaCO₃ (1.4 gpg, 1.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Três Rios 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 Três Rios water?
1.4 gpg, equal to 1.3 °dH, 2.4 °fH or 24 mg/L calcium carbonate.
What dishwasher salt setting should I use in Três Rios?
For 24 mg/L (1.3 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Três Rios?
No. With soft water a softener adds nothing.
Source
Source: Ministério da Saúde, SISAGUA – controle semestral (Saaetri), CC BY-ND 3.0 (2026). Method: figure published by the water supplier. Ministério da Saúde, SISAGUA – controle semestral (Saaetri), CC BY-ND 3.0 · Outdated figure? Tell us