Water hardness by state
How hard is the water in South Dakota?
Tap water in South Dakota averages 32.6 grains per gallon (558 ppm calcium carbonate). That number determines how fast limescale coats your water heater, shower glass and appliances.
Based on 134 measurements from 36 monitoring sites, 2018-01 → 2023-09.
Water hardness by county in South Dakota
Medians of the individual measurements recorded in each county. Hardness varies far more within a state than between neighbouring states — this is where your own figure actually comes from.
| County | gpg | mg/L | Range (mg/L) | Classification |
|---|---|---|---|---|
| Pennington County | 36 | 615 | 254–1340 | Very hard water |
| Lawrence County | 30.2 | 517 | 151–653 | Very hard water |
| Butte County | 39.2 | 671 | 209–748 | Very hard water |
| Charles Mix County | 103.5 | 1770 | 210–1960 | Very hard water |
| Custer County | 18.4 | 314 | 220–411 | Hard water |
Range shown is the 10th-90th percentile of local measurements. Counties with fewer than five samples are omitted rather than estimated.
What 32.6 gpg means in South Dakota
This is very hard water — among the harshest levels measured. Scale attacks water heaters, dishwashers and pipes fast, shortening appliance lifespan and inflating energy bills. Protection is essential.
What it does to your home
Water heater: even a thin layer of scale insulates the heating element and drives energy use up.
Appliances: dishwashers, washing machines and coffee makers scale up and fail years early.
Fixtures and skin: white spots on faucets and glass, dry skin and dull hair after every shower.
How this figure was obtained
Median of the site-level medians at 36 ambient monitoring sites in the USGS National Water Information System (134 individual measurements, 2018-01 → 2023-09). Each site is collapsed to one value first so that a heavily sampled location cannot skew the state figure; the range shown is the 10th-90th percentile across sites. This describes the raw water resource, not a specific municipal tap after treatment.
Water Quality Portal — USGS National Water Information System (NWIS), characteristic "Hardness, Ca, Mg"Statewide average — hardness varies by utility and season. Always verify with your local water quality report.
Frequently asked questions — South Dakota
Is 32.6 gpg considered hard water?
On the US scale, 0–3.5 gpg is soft, 3.5–7 gpg moderately hard, 7–10.5 gpg hard and above 10.5 gpg very hard. At 32.6 gpg (558 ppm), water in South Dakota is classified as Very hard water.
Does South Dakota have a limescale problem?
Water in South Dakota averages 32.6 gpg — Very hard water. The harder the water, the faster calcium carbonate deposits build up in water heaters, appliances and pipes. Below 3.5 gpg the risk is minimal; above 7 gpg scale becomes a running cost.
How do I find the exact water hardness at my address in South Dakota?
Check your utility's annual water quality report (Consumer Confidence Report) or your water bill, or use our free interactive hardness map. Hardness can vary widely between neighboring utilities in South Dakota.
Do I need a salt-based water softener at 32.6 gpg?
Not necessarily. Salt softeners add sodium to your water and need constant refills. LIMPEO treats limescale with an electromagnetic field — no salt, no chemicals, no maintenance — and keeps healthy minerals in your drinking water.