Why Kalamazoo's Water Comes with Minerals

Jan 14, 2016

The iron-removal room at Kalamazoo's central water plant
Credit Sehvilla Mann / WMUK

Laurie from Kalamazoo asked WMUK’s “Why’s That?” question this month. It’s one you might have asked yourself, perhaps while you pour chemicals into your sink basin, or chisel at the inside of your showerhead. Why is Kalamazoo’s water full of minerals? In other words, why is the water so hard?

Let’s start with the source.

Kalamazoo city water comes from an aquifer. If you’re picturing a giant underground pool, the public service department’s John Paquin says it’s more mushy than that.

“Ultimately it all starts with rain and snowmelt, and as it soaks through the ground it collects between particles of sands and gravels. And so when it accumulates enough that it’s productive it’s called an aquifer,” he says.
 
At Kalamazoo’s central wellfield south of downtown, Paquin stands on the porch and points out the huts that dot the lawn.

“There’s six wells here and this is where it starts. We pump the water out of the ground near 200 feet below the surface,” he says.

The Comerica building in downtown Kalamazoo is only 126 feet tall.

Paquin says it’s true: Kalamazoo’s water is pretty hard. You could even say it’s tough. It averages about 20 grains of hardness per gallon, which makes it more than twice as hard as the Lake Michigan water Grand Rapids drinks. Paquin says groundwater in this part of the state tends to be hard.

“You have a lot of dissolved minerals in it and calcium and magnesium are two of the most common ones that easily dissolve, though there are other ones like iron and manganese as well,” he says. [Correction: an earlier version of this story misstated "manganese" as "magnesium."]

When you see a white crust in the bottom of your tea kettle, think calcium and magnesium.

Inside the water plant, Paquin points out the air stripper – a big white cylinder at least two stories high that removes trace contaminants an old dry cleaners’ left nearby.

“If you look up through there you can see how high it goes,” he says at the base.

The water gets chlorinated. It gets fluoridated. But the city doesn’t take out the minerals. We’ll talk about why in a bit.

Pipes at Kalamazoo's water treatment plant.
Credit Sehvilla Mann / WMUK

How did calcium and magnesium get in the water in the first place? Western Michigan University geologist Alan Kehew says you can thank the glaciers that pushed through the region – starting 30,000 years ago and wrapping up about 15,000 years later.

“And there’s lots of ground-up limestone and dolomite that the glaciers brought down, and that’s what causes the hardness in our water,” he says.

Kehew says the ice spread hundreds of feet of materials, limestone and dolomite among them, around Southwest Michigan.

“They made our landscape totally,” he says of the glaciers.

Long before that glaciation, northern Michigan was a shallow sea.

“For example, Petoskey stones are fossil corals from those formations that outcrop up there,” Kehew says.

The glaciers pushed rocks from that sea into the south.

Kehew says rainfall around Kalamazoo has a pH of about five, meaning it’s a bit acidic.

“Then in the soil the decomposing plant matter reacts with the water that’s moving through and that makes it even more acidic. It produces carbonic acid which helps to dissolve the calcite and dolomite,” he says.

Of course, you can remove calcium and magnesium with a water softener. And many people do that because hard water is, well, hard on appliances.

If the city treats the water in other ways, why doesn’t it take out the minerals?

At the water plant, John Paquin says citywide water-softening can be done. But, he adds, it’s expensive. And while hard water might be a bother, the World Health Organization says it’s not known to cause any health problems.

Paquin says that means softening the water isn’t a priority.

“We’d rather invest other types of issues. Make sure the water’s safe and reliable,” he says.

The city does remove iron at some of its plants. Paquin says iron’s not a health issue either. But he says removal dovetails with the city’s process for cleaning organic contaminants from the water.

“It makes sense if you’re going to strip, aerate the water, to follow it up with iron removal. Then it becomes more cost-effective,” he says.

Western Michigan University geologist Alan Kehew says hard water has its upsides.
 
“Great Lakes water tends to be softer and that’s - creates another problem. If you use lake water which is soft it tends to be more corrosive and can leach lead and other harmful elements,” he says.

As Kehew notes, acidic water without corrosion control is what caused the water crisis in Flint.

What in Southwest Michigan makes you curious?