Water hardness in Sioux Falls
12.2 gpg very hard
Tap water in Sioux Falls is very hard: 12.2 gpg (209 mg/L · 11.7 °dH · 20.9 °fH).
Source: City of Sioux Falls 2025 Annual Water Quality Report (Water Division) (2025) · data checked 2026-10-19
Range across supply zones: 168–250 mg/L.
2 supply zones — hardness varies by neighbourhood; the figure above is the median.
Hardness by district / supply zone
| gpg | mg/L | ||
|---|---|---|---|
| City of Sioux Falls water plant (city-owned supply) | 14.6 | 250 | very hard |
| Lewis & Clark Regional Water System (purchased supply) | 9.8 | 168 | hard |
Sioux Falls gets water from its own plant and from the purchased Lewis & Clark Regional Water System. The 2025 report lists an average of 250 mg/L (14.6 gpg) for the city plant and 168 mg/L (9.8 gpg) for Lewis & Clark. The 209 mg/L shown here is the median of those two supplies. The report does not say how many customers get each supply, so the median is not population-weighted. Both are hard to very hard, and scale is likely.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 12.2 gpg |
|---|---|
| Utility | City of Sioux Falls Water Division |
How Sioux Falls compares
- Tap water in Sioux Falls is 35 % harder than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 504 of 1372 in the United States (1 = hardest); 63 % of these cities have softer water.
Ranking of the hardest and softest water in the United States →
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 Sioux Falls
| Brand | Setting for this water |
|---|---|
| Bosch | H03 |
| Miele | 12 °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 Sioux Falls water hard or soft?
It is very hard: 209 mg/L as CaCO₃ (12.2 gpg, 11.7 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Sioux Falls safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is Sioux Falls water?
12.2 gpg, equal to 11.7 °dH, 20.9 °fH or 209 mg/L calcium carbonate.
What dishwasher salt setting should I use in Sioux Falls?
For 209 mg/L (11.7 °dH) check your manufacturer's table: maximum level (5–7).
Do I need a water softener in Sioux Falls?
Yes, unless you are only passing through: scale damages appliances within a few years.
Source
Source: City of Sioux Falls 2025 Annual Water Quality Report (Water Division) (2025). Method: figure published by the water supplier. City of Sioux Falls 2025 Annual Water Quality Report (Water Division) · Outdated figure? Tell us