Water hardness by state
How hard is the water in Illinois?
Tap water in Illinois averages 20 grains per gallon (342 ppm calcium carbonate). That number determines how fast limescale coats your water heater, shower glass and appliances.
Auf Basis von 112 Messungen an 100 Messstellen, 2018-05 → 2023-08.
Wasserhärte nach Bezirk — Illinois
Mediane der in jedem Bezirk erfassten Messungen. Die Härte schwankt innerhalb eines Bundesstaats deutlich stärker als zwischen Nachbarstaaten — daher stammt Ihr tatsächlicher Wert.
| Bezirk | gpg | mg/L | Bereich (mg/L) | Einstufung |
|---|---|---|---|---|
| McHenry County | 24.4 | 417 | 260–544 | Very hard water |
| Mason County | 17.7 | 303 | 281–331 | Hard water |
| DeWitt County | 17.5 | 299 | 278–337 | Hard water |
| Piatt County | 19.6 | 335 | 244–352 | Hard water |
| Champaign County | 18.4 | 315 | 252–338 | Hard water |
| Kankakee County | 13.6 | 232 | 10–323 | Moderately hard water |
Der Bereich entspricht dem 10.-90. Perzentil der lokalen Messungen. Bezirke mit weniger als fünf Messungen werden ausgelassen statt geschätzt.
What 20 gpg means in Illinois
This is hard water: visible scale on fixtures within weeks, clogged shower heads, stiff laundry and a water heater working overtime. Anti-scale protection is strongly recommended.
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.
Wie dieser Wert ermittelt wurde
Median of the site-level medians at 100 groundwater monitoring sites (wells and springs — the sources most US public systems draw from) in the USGS National Water Information System (112 individual measurements, 2018-05 → 2023-08). 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 — Illinois
Is 20 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 20 gpg (342 ppm), water in Illinois is classified as Hard water.
Does Illinois have a limescale problem?
Water in Illinois averages 20 gpg — 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 Illinois?
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 Illinois.
Do I need a salt-based water softener at 20 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.