Olmsted County Hard Water Guide: Rochester Softeners (2026)

Updated October 29, 2026. General information, not legal or engineering advice. Check with the agency listed before you rely on a number or a rule.

Quick reference

Topic	What to know	Source
Rochester hardness	17 grains per gallon (about 280 ppm)	Rochester Public Utilities
Rochester source	29 wells, 389 to 981 feet deep, mainly Jordan and Prairie du Chien-Jordan aquifers	RPU 2025 drinking water report
Sodium in source water	2.25 to 8.77 ppm; home softening can raise it	RPU 2025 report
When softening helps	Hardness above about 7 gpg (120 mg/L)	MDH and MPCA softening FAQ
Salt use	About 25 bags a year for an old or poorly tuned softener vs. about 5 for a well-tuned one	Post Bulletin, quoting the Water Reclamation Plant
Chloride	State standard 230 ppm; the city plant doesn't remove chloride	Post Bulletin
Private wells	More than 36,000 in the region; homeowner responsible; free test kits	Olmsted County
Who can do the work	State water conditioning or plumbing license, plus a water conditioning contractor license	Minn. Stat. 326B.55

How hard is Rochester's water?

Rochester Public Utilities lists its water at 17 grains of hardness per gallon, or 280 parts per million. Hardness is mostly dissolved calcium and magnesium. RPU notes that hard water leaves more scale and takes more soap and detergent, and it recommends keeping a separate, unsoftened supply for cooking and drinking in homes that use a softener. Outside Rochester, hardness depends on your city water supply or your private well, so check your city's annual water quality report or test.

Where does the water come from?

RPU's 2025 report describes 29 wells ranging from 389 to 981 feet deep. They draw from the Jordan-Wonewoc, Prairie du Chien-Jordan, Prairie du Chien-Wonewoc, Jordan and Jordan-St. Lawrence aquifers, layers of sandstone and dolomitic limestone beneath southeastern Minnesota. RPU adds chlorine for disinfection, fluoride at about 0.7 mg/L, and a blended polyphosphate at about 0.5 ppm for corrosion control and to keep iron in solution.

What else is in the report?

The 2025 report lists combined radium as high as 4.9 pCi/L against a limit of 5, and gross alpha as high as 14 pCi/L against a limit of 15, both of which typically come from natural deposits. Nitrate was 0.19 ppm or less. At customer taps, the 90th percentile for lead was 7.46 ppb against an action level of 15. A softener isn't designed to address these; read the full report and ask a water treatment company about point-of-use options if you have concerns.

Softeners, salt and the Zumbro River

Every softener regeneration sends chloride down the drain. According to a Post Bulletin column, Rochester's Water Reclamation Plant does not remove chloride. On one July test day, plant influent measured 272 ppm chloride and effluent to the Zumbro measured 269 ppm, while a downstream river sample was 50 ppm. The Minnesota Pollution Control Agency's chloride standard is 230 ppm, applied to the river as a whole. The plant's environmental manager said new softeners often ship set for 30 grains, which he called overkill for Rochester water, and that an old or poorly tuned unit can use 25 bags of salt a year versus about five for a newer, well-tuned one.

The Minnesota Department of Health and MPCA advise setting the softener to your water's actual hardness, and softening only where it's needed. Toilets, hose bibs, basement sinks and most cold-water taps usually don't need softened water.

Other things to know about softening

Softening can make water more corrosive to pipes, which can contribute to lead and copper in tap water. With new copper plumbing, MDH suggests waiting a few weeks before softening so the pipes can form a protective layer.
If a city already softens its water, extra home softening isn't needed.
Salt-based softeners add sodium. That's one reason RPU suggests an unsoftened tap for drinking and cooking.

Private wells in karst country

Southeastern Minnesota's karst landscape, with sinkholes, caves, springs and fractured limestone, can let contaminants like nitrate reach groundwater more easily. Olmsted County says the region has more than 36,000 private wells, that private wells aren't regulated, and that testing and maintenance are the homeowner's responsibility. Nitrate above 10 mg/L can be harmful. Olmsted County Public Health offers free water test kits, and the nine-county TAP-IN collaborative can help eligible well owners with treatment or repairs.

Who can install a softener in Minnesota?

Under Minnesota Statutes section 326B.55, water conditioning installation and servicing must be done by someone holding a master or journeyworker plumber license or a water conditioning master or journeyworker license, and anyone offering the work needs a water conditioning contractor license. Homeowners may do the work on a home they own and live in, unless a local ordinance prohibits it, and exchanges of portable softener tanks are exempt. You can look up a company's license through the Minnesota Department of Labor and Industry, and ask your city whether a plumbing permit is required.

What does it cost?

We haven't found a reliable local source for typical Rochester-area prices, so we don't publish ranges. Cost depends on the type and size of equipment, pre-filters for well water, plumbing changes, and ongoing salt and filter costs. Get the quote in writing with the model, capacity, settings and warranty.

Questions to ask a water treatment company

What license do you hold with the Department of Labor and Industry?
What hardness did you measure, and what will you set the unit to?
How much salt should I expect to use in a year?
Will outdoor lines and toilets stay on hard water?
If I'm on a well, what else did the test show?

Common questions

How hard is the water in Rochester, MN?

Rochester Public Utilities lists its water at 17 grains per gallon, or about 280 ppm.

What should my softener be set to in Rochester?

Your measured hardness, which for RPU water is about 17 grains per gallon. Factory settings of 30 grains use more salt than Rochester water needs.

Who can install a water softener in Minnesota?

Someone with a Minnesota plumbing or water conditioning license working for a water conditioning contractor, or a homeowner working on the home they own and live in, unless a local ordinance says otherwise.

Olmsted County hard water guide (2026)