Hard water in Mahtomedi, MN

Tap water hardness
162mg/L
9.5gpg
Hard

Reported by Mahtomedi · August 2025

MN typical
160 mg/L
EPA health violations since 2016
0
Softener for 3 people
24k grain
Data
Utility report

The water in Mahtomedi carries roughly 162 mg/L of dissolved calcium and magnesium, or 9.5 grains per gallon. That is hard water. The number comes from Mahtomedi, dated August 2025.

Mahtomedi on the hardness scale, with nearby cities
060120180240300360+MN typical 160Lino Lakes: 39 mg/LLino Lakes 39North St. Paul: 56 mg/LNorth St. Paul 56Maplewood: 56 mg/LMaplewood 56Roseville: 78 mg/LRoseville 78St. Paul: 82 mg/LSt. Paul 82Woodbury: 160 mg/LWoodbury 160Shoreview: 192 mg/LShoreview 192New Brighton: 230 mg/LNew Brighton 230Lake Elmo: 249 mg/LLake Elmo 249St. Anthony: 254 mg/LSt. Anthony 254Mahtomedi 162mg/L as calcium carbonate060120180240300360+MN 160Lino Lakes: 39 mg/LLino Lakes 39North St. Paul: 56 mg/LNorth St.. 56Maplewood: 56 mg/LMaplewood 56Roseville: 78 mg/LRoseville 78Shoreview: 192 mg/LShoreview 192Lake Elmo: 249 mg/LLake Elmo 249162 mg/Lmg/L as calcium carbonate
Soft 0–60 mg/LModerately hard 61–120 mg/LHard 121–180 mg/LVery hard 181+ mg/L

Mahtomedi sits close to the typical Minnesota figure of 160 mg/L. Of the 10 nearest cities we track, 6 have softer water and 4 have harder. The range nearby runs from 39 mg/L in Lino Lakes to 254 in St. Anthony.

What 162 mg/L means at home

Expect white crust on faucets and showerheads, plus spots on dishes that come out of the dishwasher.

Kettles collect scale quickly. Water heaters build up sediment at the bottom of the tank, which makes them work harder over time.

Soap and detergent need a little more to lather, and soap scum shows up in the tub.

Hardness is not a health problem, and EPA sets no limit for it. It is a matter of scale and soap.

What to do about it

At 162 mg/L most of the trouble is scale, and only a few things deal with it.

Ion-exchange water softener

The standard whole-house fix. It swaps calcium and magnesium for sodium or potassium and needs salt plus a drain. Size it with the calculator below.

Salt-free conditioner

No salt and no drain line. It changes how minerals form scale instead of removing them, so water still tests hard.

Reverse osmosis or carbon filter

Under-sink reverse osmosis removes minerals from drinking water only. Plain carbon filters improve taste but do not soften.

Softener size for Mahtomedi

3 people × 75 gallons a day × 9.5 gpg = 2,131 grains a day. A 24,000-grain unit regenerates about every 11 days.

Size it for your household

EPA record for Mahtomedi's water system

Mahtomedi · PWSID MN1820013

No health-based violations since 2016

Serves about 8,818 people from groundwater.

Health-based
0
Monitoring or reporting
0
Open now
0

Health-based means a contaminant above its legal limit or a missed treatment step. Monitoring and reporting violations are late or missing tests and notices. Source: EPA ECHO, 2026Q3 export, violations with periods starting 2016 or later. Full EPA record.

Questions

Is Mahtomedi water hard?

Yes. It measures about 162 mg/L (9.5 grains per gallon), which the USGS classes as hard.

What is the water hardness in Mahtomedi in grains per gallon?

About 9.5 gpg. One grain per gallon equals 17.1 mg/L, so 162 mg/L divided by 17.1 gives 9.5.

What size water softener do I need in Mahtomedi?

For 3 people using 75 gallons each per day, 9.5 gpg works out to about 2,131 grains a day. A 24,000-grain softener covers that with a regeneration about every 11 days.

Has the Mahtomedi water system had EPA violations?

EPA records show no health-based violations for Mahtomedi since 2016.

Nearby cities

All 57 cities in Minnesota

Hardness data: TapWaterData US Water Hardness (utility report, August 18, 2025), CC BY 4.0. Population: US Census Bureau. Violations: EPA ECHO. How we use them.