Water hardness is defined by the level of calcium and magnesium ions in the water. This characteristic can fluctuate across Illinois, as various parts of the state exhibit different water hardness levels due to their distinct geological features and sources of water.
In Illinois, water hardness can vary from soft to very hard, contingent upon the specific location in the state. Northern Illinois, particularly areas closer to Lake Michigan, typically have softer water as a result of the large freshwater source’s influence. However, southern and central parts of Illinois might have harder water due to the local bedrock and groundwater that can contain higher concentrations of dissolved minerals.
The actual water hardness measurements in Illinois cities can shed light on the specific water conditions. Water hardness indictors are prone to changes, but numerous communities in Illinois are known to have moderately hard to very hard water levels. These hardness levels can impact the taste of water, the performance of cleaning products like soaps, and have consequences on household water-using appliances.
The water hardness levels in the state of Illinois show variation across different cities, with measurements given in parts per million (ppm) and grains per gallon (gpg). Cities such as Lockport and Batavia exhibit high hardness levels of up to 667.6 ppm, 39 gpg, and 428.0 ppm, 25 gpg, respectively. On the contrary, Springfield has a relatively lower level at 110.0 ppm, 6.43 gpg. Moreover, several cities like Chicago, Naperville, and Cicero have hardness levels measured at 141.7 ppm, 8.24 gpg. While cities such as Peoria, Rockford, and Joliet along with others did not have available data.
City | Hardness ppm (mg/L) | Hardness gpg | Information Source | Notes |
Chicago | 141.7 | 8.3 | Link | Lake Michigan |
Aurora | 135.0 | 8.0 | Link | |
Joliet | n/a | n/a | Link | Currently groundwater, will be from Chicago starting in 2030 |
Naperville | 141.7 | 8.3 | Link | Purchases from Chicago |
Rockford | n/a | n/a | Link | |
Elgin | n/a | n/a | Link | |
Springfield | 110.0 | 6.4 | Link | |
Peoria | n/a | n/a | Link | |
Champaign | n/a | n/a | Link | |
Waukegan | 130.0 | 7.6 | Link | Lake Michigan |
Cicero | 141.7 | 8.3 | Link | Purchases from Chicago |
Bloomington | n/a | n/a | Link | |
Evanston | 139.0 | 8.1 | Link | Lake Michigan |
Schaumburg | 141.7 | 8.3 | Link | Purchases from Chicago |
Arlington Heights | 139.0 | 8.1 | Link | Purchases from Evanston |
Bolingbrook | n/a | n/a | Link | |
Decatur | n/a | n/a | Link | Lake Decatur |
Skokie | 139.0 | 8.1 | Link | Purchases from Evanston |
Palatine | 139.0 | 8.1 | Link | Purchases from Evanston |
Des Plaines | 141.7 | 8.3 | Link | Purchases from Chicago |
Orland Park | 141.7 | 8.3 | Link | Purchases from Chicago |
Oak Lawn | 141.7 | 8.3 | Link | Purchases from Chicago |
Berwyn | 141.7 | 8.3 | Link | Purchases from Chicago |
Mount Prospect | 141.7 | 8.3 | Link | Purchases from Chicago |
Tinley Park | 141.7 | 8.3 | Link | Purchases from Chicago |
Normal | n/a | n/a | Link | |
Oak Park | 141.7 | 8.3 | Link | Purchases from Chicago |
Wheaton | 141.7 | 8.3 | Link | Purchases from Chicago |
Hoffman Estates | 141.7 | 8.3 | Link | Purchases from Chicago via Northwest Suburban |
Downers Grove | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
Glenview | 142.0 | 8.2 | Link | Lake Michigan via Wilmette |
Plainfield | 141.7 | 8.3 | Link | Purchases from Chicago |
Elmhurst | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission |
Lombard | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
Buffalo Grove | 137.0 | 8.0 | Link | Lake Michigan |
Moline | n/a | n/a | Link | Sources form Mississippi also sources to Silvis |
Belleville | n/a | n/a | Link | |
Bartlett | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
DeKalb | 119.8 | 7.0 | Link | Groundwater that is softened during treatment |
Romeoville | n/a | n/a | Link | |
Crystal Lake | n/a | n/a | Link | |
Carol Stream | 141.7 | 8.3 | Link | Purchases from Chicago |
Quincy | n/a | n/a | Link | Sources from Mississippi River |
Park Ridge | 141.7 | 8.3 | Link | Purchases from Chicago |
Urbana | n/a | n/a | Link | |
Streamwood | 141.7 | 8.3 | Link | Purchases from Chicago |
Wheeling | 139.0 | 8.1 | Link | Purchases from Evanston |
Carpentersville | n/a | n/a | Link | |
Hanover Park | 141.7 | 8.3 | Link | Purchases from Chicago |
Rock Island | n/a | n/a | Link | |
Addison | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
Oswego | 256.0 | 15.0 | Link | |
Calumet City | 141.7 | 8.3 | Link | Sources from Chicago |
Northbrook | n/a | n/a | Link | Lake Michigan directly, Not Chicago |
Woodridge | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
St. Charles | n/a | n/a | Link | |
Glendale Heights | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
O’Fallon | n/a | n/a | Link | Mississippi River via E. St. Louis |
Elk Grove Village | 141.7 | 8.3 | Link | Purchases from Chicago via Northwest Suburban |
Mundelein | n/a | n/a | Link | Lake Michigan |
Pekin | n/a | n/a | Link | |
Gurnee | n/a | n/a | Link | Lake Michigan via Lake Bluff |
Niles | 139.0 | 8.1 | Link | Receives via Morton Grove |
Highland Park | 132.5 | 7.8 | Link | Lake Michigan, separate intake from Chicago proper |
North Chicago | n/a | n/a | Link | Lake Michigan, separate intake from Chicago proper |
Algonquin | n/a | n/a | Link | |
Galesburg | n/a | n/a | Link | |
Lake in the Hills | n/a | n/a | Link | |
Burbank | 141.7 | 8.3 | Link | Purchases from Chicago |
Danville | n/a | n/a | Link | |
Glen Ellyn | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
Lansing | n/a | n/a | Link | Purchases from Hammond IN, which doesn’t report |
Huntley | n/a | n/a | Link | |
Wilmette | 142.0 | 8.2 | Link | Lake Michigan |
Granite City | n/a | n/a | Link | |
New Lenox | 141.7 | 8.3 | Link | Purchases from Chicago |
McHenry | n/a | n/a | Link | |
Round Lake Beach | n/a | n/a | Link | Lake Michigan via Lake Bluff |
Chicago Heights | n/a | n/a | Link | Purchases from Hammond IN, which doesn’t report |
Oak Forest | 141.7 | 8.3 | Link | Purchases form Chicago |
Vernon Hills | n/a | n/a | Link | Lake Michigan via Lake Bluff |
Lockport | 667.6 | 39.0 | Link | Used City of Lockport CCR Document on the linked page |
Batavia | 428.0 | 25.0 | Link | |
Woodstock | n/a | n/a | Link | |
Alton | n/a | n/a | Link | |
West Chicago | n/a | n/a | Link | Well water, mentions they treat to reduce hardness but don’t provide values |
Edwardsville | n/a | n/a | Link | |
Belvidere | 402.3 | 23.5 | Link | |
Morton Grove | 139.0 | 8.1 | Link | Purchases from Evanston |
Homer Glen | 141.7 | 8.3 | Link | Purchases from Chicago |
Zion | n/a | n/a | Link | Purchases from Decatur |
Collinsville | n/a | n/a | Link | |
Melrose Park | 141.7 | 8.3 | Link | Purchases from Chicago |
Westmont | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
Elmwood Park | 141.7 | 8.3 | Link | Purchases from Chicago |
Kankakee | n/a | n/a | Link | |
South Elgin | n/a | n/a | Link | |
Lisle | 144.0 | 8.4 | Link | Purchases from Chicago thru DuPage Water Commission, used Elmhurst’s number |
Rolling Meadows | 141.7 | 8.3 | Link | Purchases from Chicago via Northwest Suburban |
Freeport | n/a | n/a | Link |
ppm = Parts Per Million
mg/L = Milligrams Per Liter
gpg = Grains Per Gallon
Hard water can cause issues such as mineral buildup in plumbing and appliances, reduce the efficacy of soaps and detergents, and affect the taste of the water. A tried and true solution is the use of a water softener. A water softener, like the ones from DROP, could be a worthwhile investment.
These devices work by replacing the calcium and magnesium ions that cause hardness with sodium ions, resulting in softer water. With innovative features, easy installation, and efficient operation, DROP smart water softeners provide a solution to hard water issues, extending the lifespan of appliances, improving water taste, enhancing soap effectiveness, reducing scale build-up, and increasing the overall water efficiency in your home.