Sioux Falls Water Hardness & Quality Report (2026)
Water Hardness
21.8 grains per gallon
Source
groundwater
pH Level
8.5
neutral = 7.0
Lead
0.009 mg/L
✓ Below action level
TDS
1202.9 mg/L
Est. Daily Cost
$0.99
energy & soap waste
Source: USGS Water Quality Portal · Updated 2026
0–60
mg/L
Soft
61–120
mg/L
Moderately Hard
121–180
mg/L
Hard
180+
mg/L
Very Hard
Appliance Damage Report
In Sioux Falls, your appliances are currently losing 45% efficiency due to mineral buildup.
| Appliance | In Sioux Falls | Soft Water City | Efficiency Loss |
|---|---|---|---|
| Kettle | 1.5 yrs | 8.5 yrs | -82% |
| Washing Machine | 3 yrs | 12 yrs | -75% |
| Water Heater | 5 yrs | 15 yrs | -67% |
Regional Water Comparison
How Sioux Falls compares to its nearest neighbours
| City | Hardness | PFAS (ppt) | Risk | Source |
|---|---|---|---|---|
| ▶ Sioux Falls, South Dakota | 373 mg/L | 3.6 ppt | 🔴 Very Hard | groundwater |
| Brookings, South Dakota | 353.5 mg/L | 3.5 ppt | 🔴 Very Hard | groundwater |
| Yankton, South Dakota | 202 mg/L | 2.3 ppt | 🔴 Very Hard | groundwater |
| Sioux City, Iowa | 164.5 mg/L | 3.5 ppt | 🟠 Hard | river |
| South Sioux City, Nebraska | 338 mg/L | 4.7 ppt | 🔴 Very Hard | groundwater |
National Benchmark
How Sioux Falls compares to the USA average
| Benchmark | Hardness | Appliance Risk |
|---|---|---|
| ▶ Sioux Falls | 373 mg/L | 🔴 High |
| USA National Avg | 150 mg/L | 🟠 Moderate |
| Badger Top Rated | 8.5 mg/L | 🟢 None |
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What Makes Sioux Falls's Water Unique?
Local geology and source profile
Sioux Falls, South Dakota draws its municipal water supply from the City of Sioux Falls Public Works Water Reclamation Division, sourcing from both the Big Sioux Aquifer — a shallow glacial outwash aquifer in the Minnehaha County valley of the Big Sioux River — and the deep confined Jordan Sandstone Aquifer, a regional artesian source underlying much of eastern South Dakota at depths of 1,000–2,000 feet. Surface water intake from the Big Sioux River itself supplements supply during high-flow periods. Water is treated at the Fisher Water Treatment Plant before distribution throughout the city. Water hardness in Sioux Falls reaches 373 mg/L — extremely hard, reflecting the highly mineralised character of the region's groundwater.
Sioux Falls' extreme hardness results from the deep geology of the Upper Midwest carbonate province beneath eastern South Dakota. The Big Sioux Aquifer overlies and is hydraulically connected to sequences of Ordovician Galena and Platteville Dolomite, Devonian-age limestone, and Silurian Niagaran carbonate formations that dissolved extensively during and after Laurentide glaciation. The deep Jordan Sandstone Aquifer, though primarily a sandstone formation, draws water that has circulated through carbonate confining layers and contributes concentrated dissolved calcium and magnesium from prolonged subsurface residence. Glacial till deposited over this carbonate bedrock further enriches shallow aquifers with dissolved minerals.
At 373 mg/L, Sioux Falls residents face intense daily scale challenges. Calcium deposits coat showerheads, faucet aerators, and tile surfaces within weeks — regular descaling is essential to maintain fixture performance. Water heaters experience rapid element failure without annual professional descaling, and dishwashers consistently leave white mineral film on glassware without rinse-aid. A whole-house water softener is strongly recommended for Sioux Falls households to protect plumbing infrastructure and extend the operational life of all water-using appliances.
Geology & Source: Groundwater from the Big Sioux Aquifer (glacial outwash sand and gravel) and the deep Jordan Sandstone Aquifer — overlying Ordovician Galena–Platteville carbonate and Devonian Silurian dolomite formations of the Upper Midwest carbonate bedrock province contribute extremely high dissolved calcium, producing very hard supply at 373 mg/L.