Hardness: 12 to 22 grains per gallon
Joliet reports about 22 grains per gallon east of Midland Avenue and 12 west of it. The USGS calls anything over 10.5 grains “very hard.” Hardness is not a health issue. It is the scale in your water heater, the film on your glasses, the soap that will not rinse and the dry skin after a shower.
A salt-based water softener at the main line is the fix.
Radium: samples up to 7.18 pCi/L
Deep aquifer water in northern Illinois carries naturally occurring radium. Joliet treats for it, and the annual average stays under the federal limit of 5 pCi/L. Individual samples in the 2023 report ran as high as 7.18. The EPA says long-term consumption above 5 raises cancer risk. Radium matters when you drink it, which is why the practical fix is reverse osmosis at the kitchen sink. The full picture, including gross alpha and arsenic, is on the radium page.
Chloramine: about 2 ppm at the tap
Joliet disinfects with chloramine rather than plain chlorine. It stays in the water longer, which is good for the pipes and less good for you. It is what you smell in the shower, it dries skin and hair, and the EPA requires it be removed before water goes into an aquarium or a dialysis machine. A whole-home carbon tank pulls it before it reaches any faucet.
Private wells around Joliet
If you are on a well, none of the city treatment applies. The Illinois EPA says radium turns up in private wells across northern Illinois and only a test finds it. Iron, hydrogen sulfide and hardness are common in Will County wells. The Will County Health Department lab tests hardness for $18 and the state recommends yearly bacteria and nitrate tests. More on the well water page.
The neighbors: Crest Hill, Lockport, Romeoville, Plainfield, Shorewood
A Joliet mailing address can sit on another town's water system. Crest Hill, Lockport, Romeoville and Shorewood are deep well water like Joliet, and hard. Plainfield has been on Lake Michigan water since 2004. In the EWG Tap Water Database, every one of them shows more contaminants above EWG health guidelines than Joliet itself, including trihalomethanes, PFAS, arsenic and radium.
Not sure whose water you have? Check the utility name on your bill or just give us your address and we pull the report for your exact system. See the full service area.
Sources: City of Joliet Public Utilities FAQ and 2024 Water Quality Report, USGS hardness scale, EPA radium and chloramine guidance, Village of Plainfield, EWG Tap Water Database 2013 to 2023, Illinois EPA private well guidance, Will County Health Department laboratory.