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What is Hard Water?


*Reviewed by Ken Christopher, Senior Vice President at Rayne Dealership Corporation

You may have heard of hard water but are curious about what makes water hard. Understanding what is considered hard water is the first step toward gaining a better picture of the many ways that hard water can have an impact on your daily life.

Exploring the topic of water hardness will touch on exactly what water hardness is and what natural processes lead to hardened water. It is also a good idea to understand how hard water impacts your home and body since these effects can be a quick way to tell if you have hard water. Read on to learn exactly what hard water is to determine if you need to invest in a home water softener system.

Water Hardness Defined

For those people who have asked themselves, “what is hard water?” the answer is simple. Hard water is water with relatively high mineral content. To convert hard water to drinking water, one needs water softeners.

How Does Hard Water Form?

Water becomes hard through natural processes and mineral buildup. As groundwater moves through soil and stone, it acts as a solvent, breaking apart chemical bonds and picking up mineral ions. Water is known as the “universal solvent,which can be clearly seen in the process through which water becomes hard.

Water usually becomes hard as it moves through soil rich in dissolved calcium or magnesium. Calcium is most commonly dissolved in limestone, while magnesium typically comes from dolomite. Water can also harden as it moves through soils rich with other minerals or even metals, such as ferrous iron. Other metals that can cause hard water include aluminum, zinc, barium, and manganese.

The different minerals that hard water picks up on its way through the crust can change the impact it has around your house. For example, the buildup left behind by hard water that contains primarily calcium bicarbonate will be off-white in color, whereas water that is heavily laden with ferrous iron will leave behind reddish deposits.

Because of the way hard water forms as it slowly moves through the ground, there is a strong regional variation to the hardness of the water. There is also variation between surface water and groundwater, the latter of which typically has a much higher mineral content as it is closer to soil and stone that is rich in minerals.

How Do You Know if You Have Hard Water?

If you have lived in the same region your whole life, you may have only ever known hard or soft water. Most people are curious about how to tell if they have hard water, particularly once they become homeowners, and the impact of hard water around their house can become a source of constant frustration.

The most accurate way to know whether you have hard water, and to understand exactly how hard your water is, is to use a water hardness test kit on the water in your house. These test kits are cheap or free in most cases and can quickly tell you how hard your water is. Companies specializing in water purification, like Rayne, can also professionally test your water and tell you exactly how hard it is and what types of minerals have been found in your water supply.

If you don’t want to test your tap water yourself or have someone come out to your house and test it for you, you can also check with your municipal water supplier. Municipal water suppliers regularly assess the water they are piping through their systems. These assessments check for the presence of any contaminants, ensuring that the water reaching your residence is fit for consumption. What most people don’t know is that their water supplier also tests the mineral content of their water, and many will publish that information regularly. In contrast, softened water  can contain higher levels of sodium. 

Water quality reports are a great way to gain a better understanding of exactly what is being piped into your house from your water supplier. The tests provide an accurate snapshot of the mineral quantity of your water and what types of minerals are hardening your water.

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Is Hard Water Dangerous?

Water with a high mineral content isn’t dangerous to human health.  Most places around the United States have hard water. This is particularly true across the southwestern United States.  Multiple studies have also reinforced the understanding that, while frustrating and difficult to deal with, hard water isn’t detrimental to our overall health.

How is Hard Water Measured?

Although water can become hard by a variety of mineral and metal ions, the hardness of water definition is most often provided by the content of calcium carbonate that the water contains. 

Calcium carbonate is the most common mineral that contributes to water hardness. Look at the water quality report for your municipal water supplier or have someone come out to your house to measure your water hardness. You’ll receive a report stating the number of grains per gallon (GPG) of calcium carbonate your water contains.

By using grains per gallon to measure water hardness, you are looking at the actual quantity of calcium carbonate that your water contains. Water hardness is a spectrum, starting at soft water and going all the way to hard water, with water hardness levels increasing in between.

Typical ranges for hard water are as follows:

  • Water that measures less than 1 GPG of calcium carbonate is considered “soft”.
  • Water that measures between 1 – 7 GPG is “moderately hard”.
  • Water that measures between 7-10 GPG is “hard”.
  • Water that contains over 10 GPG of calcium carbonate is “very hard”.

The Effects of Hard Water

As hard water makes its way through your house, it leaves the minerals it contains behind as an insoluble precipitate. These insoluble mineral deposits can be unsightly, are difficult to remove, and can reduce the lifespan and efficiency of appliances. The minerals left behind by hard water will impact the health and moisture of your skin and hair. Understanding these impacts can help you make an informed decision about whether you might require a water softening solution.

Soap Scum

Soap scum is a substance created from a reaction between the hard water minerals in hard water and soap. This reaction creates an insoluble residue that is difficult to remove altogether. Soap scum appears as a whitish-grey film on surfaces that come into contact with hard water and soap. Soap scum is common in sinks, showers, shower doors, faucets, counters, tile, pipes, and other bathroom and plumbing fixtures

In a household with hard water, it is challenging to completely remove soap scum. After a thorough cleaning, you may get your bathroom surfaces looking clean, but more soap scum will inevitably form. Despite the residue’s unsightly appearance, soap scum isn’t necessarily damaging. It can, however, serve as a fertile breeding ground for mold.

Mineral Deposits

Hard water will leave behind mineral deposits on the surfaces it interacts with. These deposits are referred to as “scale.” Scaling usually appears as a whitish or green substance that has a chalky texture. The scale is primarily composed of calcium and magnesium carbonates. The mineral deposits that hard water leaves behind can also consist of iron, zinc, or other metal ions carried in your water.

There are a couple of easy places to see the effects of mineral deposits in your house. One is in appliances that heat or boil water. Dishwashers, coffee pots, and water heaters are prime suspects for mineral buildup. Boiling or heating hard water will produce a substantial buildup.

Showerheads and faucets will also accumulate mineral deposits at a higher rate than other areas in your house due to their regular contact with hard water. Over time, these mineral deposits will reduce the efficiency of how these appliances and fixtures operate. The flow of water is slowly but persistently reduced.

Flat and Brittle Hair

Hard water has long been thought of as having a negative effect on the health of our hair. Multiple experiments have confirmed this belief in recent years. Through a chemical reaction with your hair structure, the mineral ions contained in hard water are absorbed into your hair, resulting in oxidative damage. Over time, this damage produces hair that more easily breaks than hair that is washed in soft water. 

Alongside decreasing the strength of your hair itself, the mineral coating that your hard water leaves behind on your hair will weigh it down. Hard water effects on hair also include causing the hair to have less volume over time. It will also look different. Healthy hair appears vibrant and shiny. The minerals in hard water will rob the hair of its natural luster and give it a dull, matte appearance.

Dry Skin

If you live in an area with a hard water supply, you may notice that your shampoo or soap produces a weak lather. In order for the soap to lather, it must have an abundance of free molecules in water to react with. With hard water, those molecules aren’t free because they are occupied by mineral ions. When shampooing or using soap to wash your body in an area with hard water, you’ll produce a weaker lather than you would with deionized or distilled water, both of which are considered soft. 

The weak lather your soap produces isn’t just a nuisance, it also becomes harder to wash out of your hair or off of your skin. Some of the soap and shampoo you use will be left behind as a thin film. This film upsets the skin’s natural PH levels. Additionally, the barrier of minerals and soap left behind by hard water makes the moisturizers you use less effective by preventing them from completely penetrating your hair or skin. 

These effects of hard water on the skin will often be seen in sensitive areas of the body. Many people experience problems with their scalp and face. Since the problem is in your water itself, and that water makes topical treatments less effective, individuals suffering from hard water-induced skin conditions often struggle to find relief. The effects of showering with hard water are dry, irritated skin that requires transitioning to soft water to be completely addressed.

Stiff Laundry and Weakened Fabrics

If you are washing your laundry with hard water in your washing machine, you will probably have to use a fabric softener if you don’t want your clothes to be stiff. The minerals in hard water are deposited into your fabric during a wash cycle and don’t easily wash out. When you dry clothes washed in hard water you can see these mineral deposits as white streaks. They are particularly noticeable if you are washing dark clothing.

The mineral deposits left by hard water will also weaken the fabric themselves. The fibers that make up your fabric will become more dry and brittle when washed in hard water over a period of time. This will cause your clothes to wear out more quickly than they would otherwise.

Closing Thoughts

Hard water is simply water with relatively high mineral content. As the water flows through the ground, it picks up dissolved mineral ions. Most commonly, this includes calcium and magnesium, but various metals can also cause water hardness. The opposite of hard water is “soft” water, which is any water that contains less than 1 grain per gallon (GPG) of calcium carbonate. Water can be varying degrees hard if it contains more than 1 (GPG) of calcium carbonate.

While the hardening of water is a natural process, it produces some undesirable effects on our bodies and around our homes. Hard water reacts with soap to produce soap scum, an insoluble precipitate that coats surfaces and fixtures with a whitish film that is difficult to clean off. Even areas that don’t come into contact with soap will have mineral deposits left on them. These mineral deposits can leave an unsightly residue, and impact the efficiency of appliances like your dishwasher over time. 

The most effective way to address hard water is to transition to a water softening system. Water softening systems are typically installed at the municipal water supply line coming into a house so that all of the water flowing through your house is softened through a gentle deionization process. These systems are environmentally friendly, easy to maintain, and address the negative effects of hard water at their source. If you are still cautious regarding the water quality, you can utilize an at-home water testing kit to determine whether your water supply needs water treatment or not.

To learn more about how to address hard water in your home by installing a water softener, please contact Rayne Water today.


  3. Ungvarsky, Janine. “Hard Water.” Salem Press Encyclopedia of Science, 2018.
  4. Luqman, Muhammad Waqas, Muhammad Haris Ramzan, Usama Javaid, Roshan Ali, Muhammad Shoaib, and Muhammad Ayyas Luqman. “To Evaluate and Compare Changes in Baseline Strength of Hairs after Treating Them with Deionized Water and Hard Water and Its Role in Hair Breakage.” International Journal of Trichology 10, no. 3 (May 2018): 113–17.