Home » Water Quality » Hard Water » What is Hard Water? (Definition, Signs & Treatment)

What is Hard Water? (Definition, Signs & Treatment)

Scott Winfield
Written by Scott Winfield
Last Updated on

It’s interesting to think about water in terms of hardness or softness, right? After all, water is just water. But, water can actually be hard or soft depending on the concentration of its mineral content, especially in the presence of calcium and magnesium molecules.

In this article, we’re going to explain what hard water is, give you tips about its most common signs and list its potential effects.

Let’s go!

What is Hard Water?

The United States Geological Survey (USGS) classifies hard water as water that contains more than 60mg/L of calcium or magnesium carbonate. The Water Quality Association, on the other hand, defines hard water as water that has one grain of hard water minerals per gallon.

These minerals leach into the water in various ways such as:

  1. Water from the clouds evaporates and turns to rain.
  2. The water collects calcium, magnesium, iron, and other minerals as it flows through the earth.
  3. The water with minerals gets mixed with the groundwater supply.
  4. As the water flows through our pipes, the extra minerals build up as we use water each day.

The molecules of minerals such as calcium, magnesium, and iron have a tendency to stick to surfaces. So, once hard water enters your plumbing system, it can lead to mineral buildup that clogs and reduces the efficiency of appliances like washing machines, kettles, and dishwashers.

The reduced efficiency of appliances will reflect on your energy bills, and the clogged pipes will disrupt the water pressure and flow rate. Additionally, hard water can make your skin and hair dry, cause limescale formation on the surfaces it touches, and stain your laundry.

Hard water minerals also interact with the chemical ingredients in soaps and detergents, significantly diminishing their lathering properties. So, you’re most likely to notice problems commonly associated with hard water while cleaning or doing everyday tasks involving water.

Hard Water Ions

Hard water has excessive mineral ions. Most commonly, those ions are metal cations, magnesium, calcium, and sometimes manganese, iron, and aluminum. They dissolve in water (they’re water-soluble), and they have the strength to corrode metal pipes via galvanic corrosion.

Hard Water Deposits on Tap Faucet
Hard Water Deposits on Tap Faucet

The Effects of Hard Water on the Human Body

Hard water doesn’t pose any serious health threats to humans. On the contrary, it contains high amounts of magnesium and calcium, which are essential nutrients for our everyday diet. They help us maintain healthy bodily functions and strengthen our bones to prevent health conditions like osteoporosis or heart disease.

That being said, there are some ongoing studies to determine whether hard water consumed over an extended period could cause kidney problems. But, these studies are conducted with extremely hard water that’s quite rare in American households, and they don’t present conclusive arguments on how hard water negatively affects human beings.

Health concerns aside, hard water can have adverse aesthetic effects on your skin and hair. Since shampoos don’t lather well in it and since minerals tend to stick to our skin and hair, it’ll make your skin and hair look dull.

Hair can become dry and brittle from washing with hard water, not to mention that it won’t feel as clean. Hard water is probably the culprit behind limp or stiff hair with a lot of soap residue after washes.

In extreme cases, the minerals in hard water might clog the pores on our skin that allow it to breathe, which may result in congestion, irritation, and itching. This is especially common in people with sensitive skin. In other words, you make yourself susceptible to dehydrated skin and irritate pre-existing conditions like eczema. Those mineral particles from the water will absorb the natural oils in your skin, causing irritation, bumpy patches, and rashes.

Read Also:

Can You Drink Hard Water?

Hard water is safe to drink. While its taste might be unpleasant to most people, it has more health benefits than soft water because of its high mineral content. 

While drinking hard water can help you get some of the calcium and magnesium you might be lacking, bathing in it can have some adverse effects on your skin and hair. So, it might be a good idea to soften bathing water but have a different water supply for drinking.

What Does Hard Water Feel Like?

You can’t tell if you have hard water simply by looking at it, but a standard clue is if you feel a slimy film on your hands after you’ve washed them. Another sign is if you notice residue on dishes and glass items once they dry after you’ve washed and rinsed them.

You may also notice that soaps, detergents, and body washes don’t lather properly.

How to Know if You Have Hard Water (Signs)

The most common hard water signs:

  • Metallic taste in drinking water
  • Dry skin after a bath
  • Dry and dull hair
  • Clothes that look old, dull, and stained after laundry
  • Low water pressure throughout the house
  • Clogged pipes in the washing machine, dishwater, water, heater, and sink
  • Soap residue and limestone buildup in the shower and tub
Hard Water Deposit on Shower Tap
Hard Water Deposit on Shower Tap

If you notice any of the above signs, you should immediately conduct a hard water test by sending your water sample to a certified water testing lab.

How to Remove Hard Water Stains From Surfaces

Here are several guides to help you remove hard water stains from different surfaces:

What is Water Softening?

A water softener works to soften hard water either through a chemical process that removes calcium and magnesium mineral molecules or by altering their molecular structure. There are three types of water softeners:

  • Salt-based water softeners: Salt-based water softeners are water softener systems that removes hard water mineral molecules through an ion exchange process, in which the positively charged mineral ions are attracted, trapped, and replaced by negatively charged resin beads as the water passes through them. This type of softening device mostly comes with two tanks: resin tank and brine tank. A brine solution prepared in the brine tank recharges the resin beads with sodium and periodically flushes out the trapped minerals. Some salt-based water softener systems may have potassium salt instead of sodium salt in the brine tank.
  • Salt-free water conditioners: Salt-free water conditioners are devices that alter the molecular structure of hard water minerals to prevent them from sticking together. The best salt-free water softener systems use a Template Assisted Crystallization (TAC) resin to crystallize the minerals.
  • Electromagnetic descalers: Unlike the two water softener types above, you don’t need to install electromagnetic descalers, nor do they need contact with water. They come with magnetic bands that are wrapped around the main pipe. By sending electromagnetic impulses to the water as it passes through the pipe without intervention, they neutralize mineral molecules and prevent them from sticking to surfaces. You can learn more about them in our article on electronic water descaler systems article.
Water Softener Tanks
Water Softener Tanks

Benefits of a Water Softener

Here are the benefits of having a water softening system:

1. No Mineral Buildup or Limescale Formation

Soft water doesn’t have the mineral ions that build up in your appliances and pipes over time; this saves you money on high repair costs. When minerals build up inside a pipe, the path that water travels narrows, requiring a higher pump pressure to function.

Furthermore, mineral buildup will cause your system to expend more energy to keep your water cold or hot.

As mentioned earlier, hard water also leads to mineral buildup and limescale formation on appliances. You will have to repair coffee machines, dishwashers, water heaters, ice makers, and laundry machines frequently, and no matter how thoroughly you wash your clothes and dishes, they’ll have mineral stains on them.

You can eliminate all these problems by installing a water softener system.

2. Cleaner Skin and Softer Hair

When it comes to showering or bathing, soft water is tremendously beneficial for your skin and hair. Hard water is not entirely soluble in soaps due to the mineral ions, and this forms a precipitate that shows up in the form of soap scum.

Therefore, homes with a water softener can benefit from a better lather when using their soap. Hard water is harsh on hair and can cause it to feel brittle, frizzy, and dry, and it can dull the color of hair. Conversely, soft water can help balance the pH level of hair.

3. Shorter Cleaning Times

Cleaning with hard water makes chores more cumbersome and time-consuming since soaps and detergents don’t lather well with it. Hard water doesn’t always get things clean the first time, causing you to re-wash laundry and dishes.

It is not uncommon to spend unnecessary time cleaning soap scum and chalky lime off of your sinks, faucets, and showers.

Are Water Softeners Effective?

Traditional salt-based water softeners and their level of effectiveness vary depending on the amount of salt required for regeneration. The goal is to achieve a minimum amount of salt to regenerate the resin effectively.

Anything higher than the minimum required salt dosage only results in less salt efficiency. If you exceed the minimum dosage, the higher the amount of salt, the lower the salt efficiency.

Interestingly, there’s also a point at which more salt used in the regeneration process will not add to the softening capacity whatsoever, and the system will only wash it out. It presents a challenge for manufacturers of water softeners who want to promote both high capacity and high efficiency.

As you can imagine, manufacturers have to be sure to include a specific dosage. Moreover, the NSF/ANSI 44 states that water softeners with efficiency ratings cannot deliver more salt or operate at a constant maximum service flow rate greater than the listed rating.

That being established, we should also inform you that water conditioners or electromagnetic descalers are less effective than salt systems when it comes to reducing scale. While salt-free conditioners can reduce scale up to 90%, this number is only 50% for magnetic descalers.

Frequently Asked Questions on Hard Water

Below are the answers to a couple of frequently asked questions regarding hard water:

How to remove hard water naturally?

It depends on why you want to remove the water hardness.

If you want soft water for coffee or tea, boiling can be an effective method to remove calcium. When you boil water, calcium molecules bond together. In the end, they get so heavy that they accumulate at the bottom of your kettle in the shape of chalky, white sediment.

For cooking and bathing, you can use baking soda. Although it won’t completely soften your water, it’ll bring its pH to more neutral levels (7), thus providing better water for your veggies, skin, and hair. The recommended dose for a pot of water is 5.6 grams of baking soda; for bathing, you can adjust that number depending on the size of your bathtub.

You can put water softening tablets in your washing machine to have better laundry performance, improve the efficiency of the machine, and lengthen its lifespan.

Alternatively, washing soda or vinegar can eliminate the effects of hard water on laundry.
If you want to soften your aquarium water, you can put driftwood inside it. It releases tannins in the water, which soften the water naturally.

Does boiling water remove hardness?

Boiling water can remove calcium from hard water. Using a clean kettle or pot, fill it with water, place it on the stove, and set the burner high to let it boil for a few minutes.

Next, allow the water to cool and use a spoon to scoop the sediment from its surface before placing it inside a container.


Hard water is water that’s rich in mineral content, especially that of calcium and magnesium. The USGS classifies water with more than 60mg/L of calcium or magnesium content as hard water.

Although hard water doesn’t pose any health risks, its effects might give you a couple of headaches. It may clog your pipes, reduce the efficiency of your appliances, give your clothes, skin, and hair a dull and worn-out look, and cause limescale formation on any surface the water comes into contact with.

To deal with it, many American homeowners install water-softening devices. By either removing minerals or altering their molecular structures, these devices provide soft water for the whole household and eliminate the adverse effects of hard water.

Sign Up for Weekly Water Quality News & Advice

Join our 1 Million+ strong water defense community and get updated on the latest product news & gear reviews.

We HATE spam. Your e-mail will never sold or shared!

Scott Winfield
Scott Winfield
My name is Scott Winfield and researching and writing about water filters and other strategies to purify water has become my full time passion in recent years. I'm glad that you found our site and you can look forward to authoritative and well researched content here to help you get the best in water.
Leave a Reply

Your email address will not be published. Required fields are marked *