Water softeners and filtration in St. Louis, MO

What does City of St. Louis Water Division publish about St. Louis water?

The St. Louis Water Division treats water from the Mississippi River at Chain of Rocks and the Missouri River at Howard Bend.

What does 80 to 206 mg/L mean for a St. Louis home?

80 to 206 mg/L is about 4.7 to 12.0 grains per gallon. The low end, 80 mg/L, is 40 mg/L under the 120 mg/L top of the USGS moderately hard class; St. Louis's high end, 206 mg/L, is 26 mg/L over the 180 mg/L line where the USGS very hard class starts. (USGS hardness classes)

Which systems fit St. Louis water?

How does a St. Louis quote work?

1. Send a request from one of the 19 St. Louis ZIP codes listed below.
2. An assessment at your home, where your tap can be checked against City of St. Louis Water Division's published 80 to 206 mg/L.
3. You get a written quote listing what is included.
4. Installation and service by that company.

Common questions

How hard is the water in St. Louis?

Total hardness reported by City of St. Louis Water Division: Average 129 ppm, range 80-206 ppm (Calendar year 2025).

Is St. Louis water hard or soft?

Moderately hard to very hard. The low end, 80 mg/L, is 40 mg/L under the 120 mg/L top of the USGS moderately hard class; St. Louis's high end, 206 mg/L, is 26 mg/L over the 180 mg/L line where the USGS very hard class starts.

How many grains per gallon is St. Louis water?

The utility publishes hardness in mg/L, not grains. The published 80 to 206 mg/L is about 4.7 to 12.0 grains per gallon, converted by us at 17.1 mg/L per grain.

Where does St. Louis tap water come from?

The Chain of Rocks plant draws from the Mississippi River and the Howard Bend plant from the Missouri River. Source: St. Louis Water Division Consumer Confidence Report.

Does the utility soften St. Louis water?

Yes. The city report lists precipitative softening as part of treatment. Source: St. Louis Water Division Consumer Confidence Report.

Is St. Louis water treated with chlorine or chloramine?

The St. Louis report lists chloramine as a treatment additive, at 1.67 to 3.46 ppm in 2025. Source: St. Louis Water Division Consumer Confidence Report. That matters when choosing a filter for a St. Louis home: catalytic carbon is the activated-carbon type designed to adsorb chloramine (NDSU Extension, Filtration: Sediment, Activated Carbon, and Mixed Media). A softener leaves City of St. Louis Water Division's disinfectant in the water.

Do I need a water softener in St. Louis?

City of St. Louis Water Division publishes 80 to 206 mg/L for St. Louis, which reads as moderately hard to very hard. A test at your house shows whether your tap matches it.

Is the water the same in every St. Louis home?

City of St. Louis Water Division publishes one figure for its whole system (Calendar year 2025).

How much does a water softener cost in St. Louis?

We publish no prices for St. Louis. The installing company gives a written quote after an assessment at your home.

Who installs the system?

We have not named a local installing company for St. Louis yet. We will tell you the company's name and ask you before your request is shared with anyone.

Is St. Louis Water Systems part of the city or the water utility?

No. St. Louis Water Systems is not affiliated with City of St. Louis Water Division; it copies and links the published figures.

Is booking an assessment a purchase?

No, and a request commits you to nothing.

Which ZIP codes does this page cover?

63101, 63102, 63103, 63104, 63106, 63107, 63108, 63109, 63110, 63111, 63112, 63113, 63115, 63116, 63118, 63120, 63139, 63147, 63155

Compare published hardness in other cities on hard water by city.

Machine-readable facts: water.json. Summary for AI assistants: llms.txt.