Water hardness in Sumidouro
6 mg/L soft
Tap water in Sumidouro is soft: 6 mg/L (0.3 gpg · 0.3 °dH · 0.6 °fH).
Source: Ministério da Saúde, SISAGUA – controle semestral (Rio Saneamento Bl3 Sa), CC BY-ND 3.0 (2025) · data checked 2026-10-20
Range across supply zones: 4–6 mg/L.
Sumidouro, in Rio de Janeiro state, is served by Rio Saneamento Bl3 Sa. Reported hardness is 5.5 milligrams per litre, very soft, with readings from 4.4 to 5.9. The figures are from the 2025 Ministry of Health SISAGUA data.
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 | 6 mg/L |
|---|---|
| Utility | Rio Saneamento Bl3 Sa |
How Sumidouro compares
- Tap water in Sumidouro is 87 % softer than the median of the 1915 cities we track in Brazil (43 mg/L).
- By hardness it ranks 1904 of 1915 in Brazil (1 = hardest); 0 % of these cities have softer water.
- In Rio de Janeiro it is number 43 of 44 cities; the regional median is 14 mg/L.
- Nearest city with clearly harder water: Duas Barras, 16 km away (50 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 Sumidouro
| 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 Sumidouro water hard or soft?
It is soft: 6 mg/L as CaCO₃ (0.3 gpg, 0.3 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Sumidouro 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 Sumidouro water?
0.3 gpg, equal to 0.3 °dH, 0.6 °fH or 6 mg/L calcium carbonate.
What dishwasher salt setting should I use in Sumidouro?
For 6 mg/L (0.3 °dH) check your manufacturer's table: level 0–1, usually no salt.
Do I need a water softener in Sumidouro?
No. With soft water a softener adds nothing.
Source
Source: Ministério da Saúde, SISAGUA – controle semestral (Rio Saneamento Bl3 Sa), CC BY-ND 3.0 (2025). Method: figure published by the water supplier. Ministério da Saúde, SISAGUA – controle semestral (Rio Saneamento Bl3 Sa), CC BY-ND 3.0 · Outdated figure? Tell us