Is Hard Water Bad for You? (The Research Explained)

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85% of Americans are estimated to use hard water in their homes. If you’ve clicked on this post, you probably have enough knowledge about hard water to know that it’s undesirable. But why is hard water bad? Why are water softeners so popular nowadays?

In this guide, I’ll be looking at the science behind hard water, its health effects, and ultimately, whether it’s safe to drink.

πŸ’§ What is Hard Water?

Water hardness is a measure of the concentration of minerals, namely calcium and magnesium, that water contains.

The greater the concentration of calcium and magnesium, the harder a water source is.

Hardness is calculated in grains per gallon, shortened to GPG, or milligrams per liter, shortened to mg/L. Water hardness measured at more than 6 or 7 GPG is considered a problem.

How is Hard Water Measured
HardnessGrains per Gallon (GPG)Parts per Million (PPM) & mg/L
Soft<1 0 – 17
Slightly Hard1.5 – 517 – 60
Moderately Hard3.5 – 7 60 – 120
Hard7 – 10120 – 180
Very Hard>10>180

You can learn more about the difference between hard water and soft water here.

πŸ“‹ What Are the Potential Health Effects of Drinking Hard Water?

Research into the health risks of drinking hard water is limited. What we do know is that, for most people, drinking hard water is completely safe.

However, there are a few studies that highlight potential risks that are worth being aware of.

One review of studies on the potential impacts of hard water has highlighted some concerning findings, which I’ve listed below:

Cardiovascular Disease

Studies have found a link between water hardness and cardiovascular disease, even after allowance was made for climatic and socioeconomic factors. At the moment, there is no clear explanation why hard water may cause heart disease, though several theories exist.


For the most part, hard water has shown to have a protective effect on the risk of certain cancers, like gastric cancer, because of its high magnesium content. However, research has found that this protective effect may actually increase the risk of esophageal cancer and ovarian cancer.

Alzheimer’s Disease

Aluminum is a mineral that can sometimes be present alongside calcium and magnesium in hard water. Studies have linked higher concentrations of this mineral in drinking water to a higher risk of Alzheimer’s, though more evidence is needed to support this.

Related: How to remove aluminum from water

Kidney Stones

Kidney stones are mostly made up of calcium, so it’s unsurprising that some studies have linked consumption of hard water with an increased risk of kidney stones – although there is only a weak correlation between the two.

Related: Is drinking hard water bad for your kidneys?

Reproductive Effects

Some reports show a link between reproductive effects and high water hardness. In one report, there were higher incidences of reproductive failure and stillbirths in hard water regions of India. It’s thought that calcium may cause oxidative stress, although magnesium has shown some beneficial effects.

πŸ”Ž How Can I Tell If My Drinking Water is Hard?

If your drinking water is hard, and contains elevated concentrations of magnesium and calcium, you may notice several effects.

Hard water stains in faucet

Common signs of hard water include:

  • Itchy, dry skin and hair. If you shower in hard water, it’s likely that your skin and hair will be affected by the calcium carbonate and magnesium in water. These minerals combine with soap to form soap scum, which forms a layer over skin and causes dryness.
  • Less efficient appliances. Soap scum can also cause an issue in your washing machine and dishwasher, and you’ll need more soap or detergent to clean your clothes and dishes if you have hard water. Even moderately hard water can affect the efficiency of your appliances.
  • Poorly-performing water heater. The effects of hard water may also be seen in your water heater. A layer of calcium carbonate and magnesium scale deposits can form on the inside of your heater, requiring it to do more work to heat up your water.
  • White spots on your clothes and dishes. Your glassware, cutlery and clothes may all pick up white spots from water with a high mineral content. It will be difficult to remove these stains from your laundry and cookware if you don’t have softened water.
  • Mineral deposits in your bathroom. Limescale stains or deposits can form if your water is hard or even moderately hard. Scale is one of the most obvious effects of hard water. You may notice limescale around your faucets, in your sink and toilet bowl, on your showerhead and in your shower unit, and anywhere that comes into contact with hard water.

An easy way to see if your water is hard is to do the soap test. To do this test, fill a clear plastic bottle with drinking water from your faucet. Add a couple of drops of pure liquid dish soap, then put the cap on the bottle and shake it up.

Place the bottle on a flat surface and examine the water. If your water looks cloudy or milky, and hasn’t formed a layer of bubbles on the surface, you’re dealing with hard water. On the other hand, if your water is clear, with a layer of fluffy bubbles on the surface, you have soft water.

🚰 Is It Safe to Drink Hard Water?

Ultimately, yes, it is likely safe to drink hard water. The most known health problems linked to calcium and magnesium are related to skin and hair. These problems are caused by showering and washing your hands in hard water, not drinking it.

The potential health risks of drinking hard water are certainly not well-documented issues – it’s important to note that most of the evidence in this article is based on singular studies that haven’t been backed up by further studies or research.

Hard water spots on glass
Source: United States Geological Survey (USGS)

Drinking hard water, if anything, is actually good for you, as our bodies require calcium and magnesium. However, we get plenty of these minerals from our diets, so it isn’t essential that we drink them in our water.

While hard water is safe for consumption, you may still prefer to soften your water because of the hardness effects on your skin, hair, and home. In that case, I would recommend considering a water softening solution.

You have multiple choices: water softeners, which remove hardness minerals from water, and water conditioners, which alter the makeup of these minerals and prevent them from being able to stick to surfaces and cause scale. You can learn more about these softening solutions in our water softener vs water conditioner guide.

Water Softener
Water Softener
springwell futuresoft salt free water conditioner
Water Conditioner

❔ FAQs

Are There Any Health Risks Of Soft Water?

Generally, no – soft water doesn’t pose any health risks. However, if you’ve used a water softening system that adds sodium to water, your drinking water may pose an increased risk of high blood pressure.

With that said, water softening with sodium is usually only a concern for people who need to follow low-sodium diets. For most people, the sodium in soft water won’t be enough to have any known effects. Water softeners can also use potassium as a salt alternative.

How Can I Know For Sure If My Water Is Hard?

Perhaps you know that your water is hard, but you can’t be sure exactly how hard it is. You can assess the hardness of water using hardness strips, which you can buy online for less than $5. These strips will tell you the hardness of water in GPG or mg/L, giving you a clearer idea of how much calcium and magnesium your water contains.

Total Hardness Test Strips
Water Hardness Strips

You could also get your water quality tested by a certified laboratory, which should give you an even clearer result.

water testing with tap score

When Is Water Considered Hard?

If your water contains less than 60 mg/L of calcium carbonate, it’s soft. If your water measures between 61-120 mg/L, it’s considered moderately hard. If it has a reading of 121-180 mg/L, it’s considered hard. Very hard water is anything measuring 180 mg/L or above. Even moderately hard water can be damaging in your home, and many people decide to invest in a beneficial softening solution if their water hardness is more than 60 mg/L.

  • Jennifer Byrd
    Water Treatment Specialist

    For 20+ years, Jennifer has championed clean water. From navigating operations to leading sales, she's tackled diverse industry challenges. Now, at Redbird Water, she crafts personalized solutions for homes, businesses, and factories. A past Chamber President and industry advocate, Jennifer leverages her expertise in cutting-edge filtration and custom design to transform water concerns into crystal-clear solutions.

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