What's in Rosemount's Tap Water? Here's the Truth

TLDR

• Rosemount's Well #8 averaged above the state standard for gross alpha radiation across four quarterly tests in 2025.
• The city mailed a notice to residents on February 13, 2026.
• This is NOT a declared health emergency — you don't have to stop drinking tap water right now.
• The city is working on a fix. Timeline: a few months to a few years depending on the solution chosen.
• Updates: rosemountmn.gov/waterquality

You probably got a letter in the mail a few weeks ago. Maybe it went in the recycling. Maybe it's still sitting on your counter. Either way — here's what it actually says, what it doesn't say, and what's happening next.

What Happened

The Minnesota Department of Health requires cities to test drinking water wells on a regular schedule. For gross alpha radiation, that testing happens quarterly — four times a year.

In 2025, Rosemount's Well #8 was tested four times. When the city averaged those four results, the annual average came in above the state's standard. That triggered a legal requirement to notify residents and develop a response plan.

The city mailed out the notice on February 13, 2026. Three residents showed up at the March 3 council meeting specifically to ask questions about it.

What Is Gross Alpha Radiation?

Here's the plain-language version: gross alpha radiation is a naturally occurring thing in groundwater. It comes from radioactive elements — like radium — in soil and bedrock that slowly dissolve into underground aquifers over millions of years. It's not from a spill. It's not from the Meta data center. It's geology.

It's also something the Minnesota Department of Health and other states regulate carefully because long-term exposure above certain levels can carry health risks — which is why there's a limit in the first place.

This isn't unique to Rosemount. Many Minnesota communities deal with naturally occurring contaminants in groundwater. The city already deactivated Well #7 voluntarily in late 2024 after PFAS (a different set of contaminants) were detected there.

Is It Safe to Drink the Water?

According to the city and the Public Works Director who spoke at the March 3 meeting: yes, for now. The letter itself — and the city's official statement — do not require you to use an alternative water source or install a home filtration system.

The water is not in violation of the EPA's Maximum Contaminant Level (MCL). What triggered the notice was the state's annual average standard being exceeded. There's a difference between those two thresholds, and the city is required by law to notify residents and act when the annual average is crossed.

One resident asked what radiation level becomes a genuine danger. The Public Works Director didn't have a precise off-the-cuff answer — it depends on the specific contaminant, the exposure level, and the duration. The city will be working with the MN Department of Health on their response.

If you're concerned, a reverse osmosis system can reduce gross alpha radiation. The city mentioned that option, though they were clear it's not required.

What Is the City Doing About It?

The city has been working on this for about a month already. Rough timeline:

• Next few months: Staff develop options and bring recommendations to the city council.
• Then: Council decides which direction to go.
• Construction/implementation: Could take one construction season (adjusting wells) up to three years (full citywide water treatment plant).

Options range from adjusting which wells are used and blending water sources, all the way up to building a centralized treatment facility. The more comprehensive the fix, the longer it takes and the more it costs.

The city's dedicated updates page: rosemountmn.gov/waterquality. For annual water quality reports: rosemountmn.gov/255/Water-Quality-Report.

The Bottom Line

The water quality letter was real, the concern is valid, and the city is required to act on it. But "required to act" doesn't mean "crisis happening right now." The city is being transparent and has committed to ongoing public updates.

For specific questions, call Rosemount Public Works: 651-322-2022. They've invited residents to do exactly that.

The next council meeting — March 17 at 7 p.m. — is expected to include a more detailed staff update on water quality options.

FAQ

Do I need to stop drinking Rosemount tap water?

No — the city and the public notice both say this is not a health emergency and no alternative source is required right now.

How long has Well #8 had this issue?

The four tests that triggered the notice were all from 2025. The state tests quarterly, so the issue was caught within the normal monitoring cycle.

What is gross alpha radiation, exactly?

It's a natural type of radiation from elements like radium dissolving from soil and bedrock into groundwater. Regulated because long-term exposure above certain levels can pose health risks.

Will my utility rates go up because of this?

Too early to say. If the city builds a water treatment facility, that would eventually affect utility costs. No decisions made yet.

Where can I get updates?

rosemountmn.gov/waterquality. Or call Public Works at 651-322-2022.