What Does a Water Softener Actually Remove?

A traditional water softener is primarily designed to address hardness.

Hard water contains dissolved minerals—primarily calcium and magnesium. As water travels through rock and soil, it picks up these naturally occurring minerals before eventually reaching a well or municipal water supply.

Calcium and magnesium generally aren't what we think of as drinking-water contaminants. But they can create problems throughout a home.

Hard water can contribute to:

• Scale buildup on faucets and shower doors

• Spots on dishes and glassware

• Mineral accumulation inside water heaters

• Reduced efficiency of water-using appliances

• Soap and detergent performance issues

• Dry-feeling skin and hair

A properly designed water softener addresses hardness through a process called ion exchange.

In simple terms, the system exchanges hardness minerals such as calcium and magnesium for other ions, typically sodium or potassium.

The result is softened water throughout the home.

But nitrate is a different issue.

Why Doesn't a Normal Water Softener Remove Nitrate?

The fact that water softeners use ion exchange can create some confusion.

There are specialized ion-exchange treatment systems that can be designed specifically for nitrate reduction. However, that does not mean a conventional residential water softener should be expected to remove nitrate.

Traditional softeners are designed around removing positively charged hardness ions such as calcium and magnesium.

Nitrate behaves differently in water and requires treatment specifically designed and validated for nitrate reduction.

So if a water test shows elevated nitrate, don't assume the softener in your basement is taking care of it.

A conventional water softener is not a nitrate treatment system.

Soft Water Isn't the Same as Purified Water

This is one of the most important distinctions homeowners can understand about water treatment.

A softener can dramatically improve how water behaves throughout your home without necessarily addressing contaminants in the water you drink.

Your shower can feel better.

Your glassware can look better.

Your fixtures can have less scale.

Your water heater can be better protected.

And nitrate can still be present in your drinking water.

That's because water conditioning and drinking-water purification are different jobs.

Water for the Home. Water for the Body.

This is the easiest way I've found to explain residential water treatment.

Think about your water in two categories:

Water for the home.

This is the water flowing through your water heater, dishwasher, washing machine, showers, faucets, fixtures, and plumbing.

Hardness, iron, manganese, scale, staining, and certain taste or odor issues can affect water throughout the house. Whole-home treatment is designed around those problems.

Then there is:

Water for the body.

This is the water your family drinks, cooks with, makes coffee with, uses for ice, fills reusable water bottles with, and uses for food preparation.

That's where drinking-water treatment comes into the conversation.

The system designed to protect your plumbing doesn't necessarily do the same job as the system designed to improve the water you're putting into your body.

How Can Nitrate Be Reduced?

One commonly used technology for nitrate reduction in residential drinking water is reverse osmosis, or RO.

Reverse osmosis works very differently from a conventional water softener.

Water is forced through a specialized membrane that allows water molecules to pass while reducing many dissolved substances.

When properly designed and certified for the application, an RO system can significantly reduce nitrate in drinking water.

But nitrate doesn't have to be the only reason someone chooses reverse osmosis.

Depending on the particular system and its certifications, RO can reduce a much broader range of dissolved substances and contaminants. These may include nitrate, lead, arsenic, certain PFAS compounds, salts, minerals, and other substances.

That's why I generally view RO as a drinking-water system, not simply a nitrate filter.

Does Every Reverse Osmosis System Remove Nitrate?

Don't assume that it does.

This is where certification becomes important.

There are many reverse osmosis systems on the market, and they don't all carry the same contaminant-reduction claims.

If nitrate reduction is important to you, ask a very specific question:

“Is this exact system independently certified for nitrate reduction?”

Then ask to see the documentation.

Look at the specific model, the certification, the contaminant-reduction claim, and the manufacturer's performance data.

A product being called “reverse osmosis” isn't enough by itself.

The treatment claim should be documented.

What If My Nitrate Level Is High?

Start with a proper water test.

For private-well owners in Iowa, regular nitrate testing is particularly important because nitrate has no color, taste, or odor.

You cannot look at a glass of water and determine whether nitrate is present.

If testing shows nitrate above the applicable drinking-water standard, take the result seriously and work with qualified professionals to determine the appropriate next steps and treatment.

Don't rely on the fact that you already own a water softener.

And don't assume that boiling the water will solve the problem. Boiling water does not remove nitrate and can actually increase its concentration as water evaporates.

Treatment needs to be designed for the contaminant you're trying to reduce.

Can I Have Both a Water Softener and Reverse Osmosis?

Absolutely.

In fact, they complement each other because they're solving different problems.

The softener can treat hardness throughout the home, helping protect plumbing, fixtures, water heaters, and water-using appliances.

The reverse osmosis system can provide treated drinking water at the locations where your family consumes it.

One system handles water for the home.

The other handles water for the body.

That doesn't mean every Iowa home needs both systems. It means homeowners should choose treatment based on their actual water conditions and what they're trying to accomplish.

Test First. Treat Second.

This is a theme you'll hear from me repeatedly because it's one of the most important principles in water treatment.

Don't start by asking which piece of equipment you should buy. Start by understanding your water.

If you're on a private well, that means appropriate laboratory testing—including regular nitrate and bacteria testing.

If you're on municipal water, start by reviewing your utility's annual water-quality report and consider additional testing when there is a specific reason or concern.

Once you know what's in the water, you can determine what—if anything—you want to treat.

The Bottom Line

Does a conventional water softener remove nitrates? No.

A traditional water softener is designed primarily to remove hardness minerals such as calcium and magnesium. It can make an enormous difference in how water performs throughout your home, but it shouldn't be confused with a drinking-water purification system.

If nitrate is a concern, test your water and choose treatment specifically designed and independently certified for nitrate reduction.

Most importantly, understand what each piece of water-treatment equipment is actually designed to do.

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:
Iowa Department of Natural Resources — Private Well Program
Iowa Department of Health and Human Services — Nitrate & Drinking Water
U.S. Environmental Protection Agency — Nitrate in Drinking Water
NSF — Drinking Water Treatment & Certification