What Makes Water Hard?

Water naturally picks up minerals as it moves through soil and rock.

Two of the primary minerals responsible for water hardness are calcium and magnesium.

The amount of those dissolved minerals determines how hard the water is.

Hardness is commonly reported as either grains per gallon (gpg) or milligrams per liter (mg/L) expressed as calcium carbonate.

The higher the concentration, the harder the water.

Hardness itself generally isn't considered a health concern. Calcium and magnesium are naturally occurring minerals.

The problem is what those minerals can do inside your home.

What Does Hard Water Do?

If you've lived with hard water for a long time, you may not even realize how many things you're seeing are related to water hardness.

Hard water can contribute to:

• White scale around faucets and fixtures

• Spots on dishes and glassware

• Buildup on shower doors

• Mineral deposits inside water heaters

• Scale inside plumbing and water-using appliances

• Increased soap and detergent use

• Soap scum in showers and tubs

• Laundry that doesn't feel as soft

• Skin and hair that can feel dry after bathing

Most of these aren't problems with the safety of the water.

They're problems with how the water performs.

And because we use water everywhere in our homes, the effects can show up everywhere too.

So What Is Soft Water?

Soft water is water that contains very little calcium and magnesium hardness.

In a home with naturally hard water, this is typically accomplished with a water softener.

Most residential water softeners use a process called ion exchange.

As hard water passes through the softener, calcium and magnesium ions are exchanged for sodium or potassium ions. The hardness minerals are captured by the system, and softened water continues into the home.

Periodically, the softener regenerates to clean and recharge the treatment media so the process can continue.

The result is water that behaves very differently throughout the house.

What Does Soft Water Feel Like?

This is usually one of the first things people notice.

When someone who has lived with hard water showers in properly softened water for the first time, they'll sometimes describe the water as feeling “slippery.”

That doesn't mean there's something in the water making it slippery.

With hard water, calcium and magnesium react with soaps and shampoos. That interaction can leave residue behind and make it more difficult for soap to rinse and perform the way it was intended.

With soft water, that reaction is greatly reduced.

Soap lathers more easily and rinses differently. Your skin's natural oils aren't being covered by the same mineral and soap residue you're accustomed to feeling.

For someone who has spent years showering in hard water, soft water can initially feel unusual.

Usually, people get used to it pretty quickly.

Why Does Soap Work Differently With Soft Water?

This is one of the biggest practical benefits of softened water.

Hardness minerals interfere with soap.

That's why homeowners with hard water often use more:

• Shampoo

• Body wash

• Dish soap

• Laundry detergent

• Cleaning products

With soft water, you generally need less soap and detergent to accomplish the same job.

This is also why one of the first things I tell someone after installing a softener is:

Cut back on the soap.

If you use the same amount you used with hard water, you'll probably be using too much.

What Happens to Appliances?

Hardness doesn't just show up on the faucet.

It can also create scale anywhere water is heated or evaporates.

That makes water heaters especially important.

As hard water is heated, mineral scale can accumulate inside the equipment. Similar buildup can occur in dishwashers, coffee makers, humidifiers, showerheads, fixtures, and other water-using equipment.

A water softener helps prevent that hardness scale from forming.

I like to think about water treatment this way:

You can see the scale on your shower door.

You can't see what's happening inside your water heater.

But it's the same water.

Is Soft Water Safe to Drink?

For most people, properly softened water is suitable for normal household use.

However, soft water and purified drinking water are not the same thing.

This is an important distinction.

A conventional water softener primarily addresses calcium and magnesium hardness. It isn't designed to remove every contaminant that may be present in drinking water.

For example, you shouldn't assume that a standard water softener removes nitrate, PFAS, lead, arsenic, bacteria, or other potential drinking-water contaminants.

That's a different job.

Water for the Home. Water for the Body.

This is the simplest way I know to explain the difference.

Water for the home is the water running through your plumbing, water heater, dishwasher, washing machine, showers, faucets, and fixtures.

That's where softening can make an enormous difference.

Then there's water for the body—the water your family drinks, cooks with, uses for coffee and ice, and puts into reusable water bottles.

Depending on the home's water and the family's goals, drinking-water treatment such as reverse osmosis may be used for that purpose.

A softener and a drinking-water system aren't competing technologies.

They're designed to do different jobs.

Does Everyone Need a Water Softener?

Not necessarily.

The first thing I want to know is how hard your water actually is.

Some water supplies are naturally softer than others. Hardness can also vary considerably between municipal systems and private wells.

That's why I don't believe homeowners should start by shopping for equipment.

Start by understanding your water.

Have the hardness measured. Learn about your water source. Look at the problems you're experiencing around the home.

Then decide whether treatment makes sense.

How Do You Know If You Have Hard Water?

There are some obvious clues.

Scale around faucets, spots on glassware, buildup on shower doors, and excessive soap use can all point toward hard water.

But testing is simple and gives you a much better answer.

Once you know the hardness level, a water-treatment professional can properly size and configure a softener for the home's water conditions and water usage.

Sizing matters.

A system that's too small, improperly programmed, or inefficiently configured may use unnecessary salt and water or fail to consistently provide soft water.

The goal isn't simply to install a water softener.

The goal is to properly treat the water.

The Bottom Line

Soft water isn't complicated.

It's water with the hardness minerals—primarily calcium and magnesium—removed or significantly reduced.

Those minerals generally aren't a drinking-water health concern, but they can have a significant effect on your plumbing, appliances, fixtures, cleaning, laundry, skin, hair, and overall experience with water throughout your home.

A properly designed water softener addresses those hardness problems.

But remember:

Soft water isn't the same thing as purified water.

Understand your water. Determine what you're trying to improve. Then choose treatment designed specifically for that job.

Water for the home. Water for the body. Different water problems require different solutions.

About Brook Haas

Brook Haas is the owner of BrightWater Kinetico in Central Iowa and has more than 16 years of experience in the water-treatment industry. He works with homeowners, businesses, builders, and community organizations to better understand local water-quality challenges and identify appropriate treatment solutions.

Suggested website resources:
U.S. Geological Survey — Hardness of Water
Iowa Department of Natural Resources — Drinking Water
Water Quality Association — Water Hardness & Softening