Where it comes from
Joliet draws most of its water from 21 deep wells drilled about 1,000 feet into the Ironton-Galesville sandstone, plus five shallow wells. Radium is a naturally occurring element in that rock, and water that sits in it for centuries picks it up. This is not a Joliet problem so much as a northern Illinois deep-aquifer problem. Crest Hill, Lockport, Romeoville and the other towns on the same sandstone deal with it too. The Illinois Department of Public Health has published fact sheets on it for years.
What the city does about it
Eleven of Joliet's treatment plants remove radium with hydrous manganese oxide, HMO, a process the city says takes out up to 90%. That is real treatment and it is why the annual average lands under the limit. It is also why the 2023 range runs from 0.462 up to 7.18: some wells and some plants do better than others, and the water at your tap depends on which ones feed your street.
The federal standard is 5 pCi/L for combined radium 226 and 228, judged on a running annual average. The EPA sets it there because drinking water above the limit over many years raises the risk of cancer. Joliet did not violate the standard in 2023. A single sample at 7.18 is not a violation. It is also not nothing.
The other radioactivity line
The same report lists gross alpha, a broader measure of alpha radiation that includes radium and other isotopes, with a highest 2023 result of 19.3 pCi/L against a limit of 15. And it lists arsenic, another naturally occurring element in this aquifer, with a high of 10.1 parts per billion against a limit of 10. Both pass on the annual average. In the EWG Tap Water Database, radium is flagged at 31 times EWG's own health guideline and arsenic at 266 times. EWG guidelines are much stricter than federal law; the point is the direction, not the multiplier.
What does not work
- Boiling. Water boils off, radium stays behind and gets more concentrated.
- Pitcher and faucet carbon filters. Carbon is for chlorine, taste and odor. Radium is a dissolved metal and passes straight through.
- Whole-house carbon tanks. Same reason. Ours is there for the chloramine, not radium.
- Bottled water forever. It works, it is expensive, and you still cook with tap water.
What works
The EPA lists ion exchange, reverse osmosis and lime softening as the treatments for radium. Lime softening is a plant-scale process. Ion exchange is what Romeoville runs at its plants and, in a smaller way, what a salt-based softener does at your main line. Reverse osmosis is the one that fits under a kitchen sink and treats the water you actually drink and cook with, with a dedicated faucet, and it also handles the arsenic and dissolved solids in the same pass. That is the piece of the bundle built for this page. Read about the under-sink reverse osmosis system.
Radium matters when you drink it. Showering and laundry are not the exposure route, which is why we do not push whole-house RO. The softener and carbon tank handle the rest of the house, and the RO handles the glass. All three installed for one price on the pricing page.
On a private well
None of the city treatment applies to you. The Illinois EPA says radium is found in private wells across northern Illinois and only a test finds it. Get the test, and if radium shows up, the RO at the kitchen sink is the answer for drinking water. More on well water treatment in Will County.
Sources: City of Joliet 2024 Water Quality Report (2023 data: radium 0.462 to 7.18 pCi/L, gross alpha 19.3, arsenic 10.1 ppb, 21 deep and 5 shallow wells, 11 plants with HMO treatment); EPA radionuclides rule and radium treatment guidance; Illinois Department of Public Health radium fact sheets; Illinois EPA private well guidance; EWG Tap Water Database (Joliet, 2013 to 2023 data).