Water Hardness Map

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Find the expected water hardness at your address

Water in the Madison area comes from an underground aquifer and has dissolved calcium and magnesium minerals in it, which makes the water “hard.” These minerals in our water are not harmful to human health; you can view educational information from the U.S. Geological Survey on water hardness. Hardness varies by location and over time, so it is important to ensure the hardness setting on your water softener reflects the water coming in as accurately as possible. You can use the water hardness map below to help determine the proper setting.

The water hardness map and chart provide an expected hardness for your address. These estimates, reported in grains, were developed with local water utilities and should be used to set softener efficiency. Water hardness is not a single static number. There are very small, natural fluctuations in local groundwater over time. These numbers come from water utilities that have used laboratory testing and historical data to determine mineral content. Color-changing test strips and titration field tests have been shown to be error-prone and produce unreliable results.

Search for an address in the District’s service area using this map. Click the colored area that the address occupies to see the expected hardness for that address.

Areas in gray are not served by the District or are not connected to public water sources. If you live in one of these areas, check with your community’s water utility, or if on a private well, test for hardness by completing multiple tests.

MunicipalityHardness in grains
Cottage Grove

20

Deforest

32

Fitchburg

Multiple; see map

Madison

Multiple; see map or Madison Water Utility website

Maple Bluff

Multiple; see map

McFarland

21

Middleton

18

Monona

24

Morrisonville

20

Shorewood Hills

Multiple; see map

Town of Madison

Multiple; see map

Verona

20

Waunakee

15

Windsor

20

Note on method: The water utilities that determined these numbers did so through laboratory testing
of mineral content. Where possible, following the reported numbers from the water utility is a better bet than
using test strips. Contact us for full sources and metadata.