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What Is Hard Water? (Definition, Signs & Treatment

Scott Winfield
Written by Scott Winfield
Last Updated on

Limescale buildups in your pipes and appliances? Dry skin and hair? Struggling to get soap to lather?

Sounds like your home has hard water. But what does that even mean?


In this guide, we explain what hard water is, how to identify it, what you can do to prevent it, and plenty more. So, let’s get into it!

What Is Hard Water?

Hard Water

The United States Geological Survey (USGS) classifies hard water as water that contains more than 60 mg/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 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. This mineral-rich water 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.

Mineral molecules such as calcium, magnesium, and iron tend 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 can increase your energy bills, and clogged pipes can disrupt your 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.

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 have the strength to corrode metal pipes via galvanic corrosion.

The Effects of Hard Water on the Human Body

How Does Hard Water Cause Dryness

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 we should consume on a daily basis. 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 consuming hard water over an extended period could cause kidney problems. However, 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 with hard water and the minerals tend to stick to our skin and hair, it can make them look dull.

Plus, hair can become dry and brittle from washing with hard water, and it usually doesn’t feel as clean.

In extreme cases, the minerals in hard water might clog the pores in our skin, which can result in congestion, irritation, and itching. This is especially common in people with sensitive skin.

This can make you more susceptible to dehydrated skin and irritate pre-existing conditions like eczema. The mineral particles in the water can also absorb the natural oils in your skin, causing irritation, bumpy patches, and rashes.

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Can You Drink Hard Water?

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

As a result, drinking hard water can help you get some of the calcium and magnesium you might be lacking. Yet, as mentioned, bathing in it can have some adverse effects on your skin and hair. So, it might be a good idea to soften your bathing water but to still drink harder water, if possible.

One way to do it is to use a water softener that includes a remineralizer. This will remove hard water minerals from your water but reintroduce small amounts of calcium and magnesium in the final stage of filtration. As a result, you get the best of both worlds: water that’s soft enough for bathing and drinking water that contains beneficial minerals.

What Does Hard Water Feel Like?

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

How to Know if You Have Hard Water (Signs)

Signs of Hard Water

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 limescale buildup in the shower and tub

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?

Salt-Based Water Softeners

Water softening is the process of removing magnesium and calcium from hard water, or altering their molecular structures to crystallize them. To do this, you need to install a water softener, and there are three main types:

  • Salt-based water softeners: Salt-based water softeners are water softener systems that remove hard water mineral molecules through an ion exchange process. During the process, 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: a resin tank and a 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 water 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.

Benefits of a Water Softener

Here are the benefits of having a water-softening system:

1. No Mineral Buildup or Limescale Formation

Water softeners remove or crystallize the hard water minerals that cause limescale buildups in pipes and appliances. This is highly beneficial as it reduces the number of repairs and replacements you have to pay for.

In fact, water softeners can increase the longevity of most household appliances including coffee machines, dishwashers, laundry machines, and water heaters.

2. Cleaner Skin and Softer Hair

When it comes to showering or bathing, soft water is tremendously beneficial for your skin and hair. On the other hand, hard water isn’t entirely soluble in soaps due to the mineral ion content, and this forms a precipitate that shows up in the form of soap scum. Therefore, if you have a water softener you should get a better lather when using soap.

Hard water is also harsh on hair and can cause it to feel brittle, frizzy, and dry. Conversely, soft water can help balance the pH level of hair, and keep it looking shiny and healthy.

3. Shorter Cleaning Times

Cleaning dishes and clothes with hard water is more cumbersome and time-consuming due to the issues with lathering we mentioned earlier. As a result, it often means having to re-wash items to get them as clean as you want them to be.

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

By using a water softener, you can greatly reduce cleaning times—your clothes and dishes should be clean after the first wash.

Are Water Softeners Effective?

As with all other household appliances, the effectiveness of water softeners varies greatly between different brands and models. The most effective salt-based water softeners on the market can remove up to 95% of magnesium and calcium from hard water, leading to a huge improvement in your home’s water.

However, there are several factors that can alter the effectiveness of a water softener, such as:

  • Initial water hardness: Some systems struggle to deal with extremely hard water as their resin beds quickly become clogged with hard water mineral particles. So, it’s essential you choose a softener that can handle the requirements of your home.
  • Improper regeneration: The regeneration process is vital for a softener to perform effectively. During this process, the resin bed is flushed with brine solution to remove trapped hard water mineral particles and recharge the resin beads. If a softener’s regeneration process isn’t functioning properly, the system won’t be as effective, and it may stop working altogether.

Another thing to bear in mind is that water conditioners and electromagnetic descalers are less effective than salt systems when it comes to reducing scale. While salt-free conditioners can reduce scale by 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 do you remove hard water without a water softener system?

Boiling can be an effective method for removing calcium. When you boil water, the calcium molecules bond together, and 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), 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 also put water-softening tablets in your washing machine to enhance its cleaning 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 use driftwood. This releases tannins which soften the water naturally.

Are there DIY test kits for water hardness?

Yes, there are many companies that provide DIY test kits for water hardness. The methods for using them can vary, but you generally need to follow these steps:
Fill the tube with tap water up to the designated line.
Dip a test strip in the water for the specified amount of time (check the instructions).
Compare the color change in the strip to the chart provided with the kit.
Just bear in mind that DIY test kits aren’t as accurate as tests you send away to a lab.


Although hard water doesn’t pose any health risks, its effects might give you a couple of headaches. It can 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. At Water Defense, we recommend using water softeners as the best solution to hard water.

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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.
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