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May 04, 2023 10 min read

Drinking water is our most crucial foodstuff, indispensable for human health. Due to the potential of drinking water becoming compromised in the future, there are adaptations being made to the production of drinking water.

There will be an increase in the need for finding alternatives to conventional drinking water sources in the future.

Two methods used are the installation of filters and the use of desalinated seawater. Both methods have the side effect of lowering the concentration of essential nutrients, such as calcium and magnesium in the drinking water. 

Does this cause any issues that we need to be aware of?  

Many people don’t like “hard” (i.e., mineral-heavy) water, for whatever reason and opt to get water softeners to extract minerals from the water.

Is “soft” water good for us or is it harmful?

Today we will take an in-depth look into these questions and much more on what we know about the effects of hard and soft water on the environment and especially our health.

What is hard water?

The name “hard water” has nothing to do with the way the water feels. Water is hard when it has a higher than usual concentration of minerals, primarily calcium and magnesium carbonates.

Water can become hard naturally as it accumulates minerals from rocks as it flows through rivers, streams, and wells.

Because calcium generally predominates this mix, the degree of “hardness” is most commonly measured in terms of milligrams of calcium carbonate per liter of water.

As a standard measure, any water sample containing less than 60 mg/L is considered “soft” whereas anything greater than that is “hard”.

Although hard water is generally thought of as safe to drink, cook with, and bathe in, many municipalities have water treatment plants that filter out as many minerals as possible.  Approximately 85% of U.S. homes have water that is considered hard.

Issues with hard water

It interferes with soap and detergents: The metallic ions in hard water often bind with various components in soap, hindering its foaming action and essentially making it ineffective at removing soil or bacteria. In addition, this binding reaction forms a precipitate on your skin that remains long after you washed and rinsed the soap bubbles away. In addition, clothes laundered in hard water can be stiff and dishes spotty.

It can be destructive to plumbing: Mineral deposits can stick to the surfaces of pipes causing a buildup known as scale. In small quantities, this is harmless, however, over time this insoluble material can coat pipes as well as the insides of appliances, restricting water flow and causing a decrement in function. Consequently, more repairs are needed and careful monitoring is needed to prevent clogging.

It requires more energy to heat water: The deposits that develop in hot water heaters can create a coating that prevents heat transfer to the water. Therefore, the water is not heated as easily, and more energy is needed to do the job. Naturally, this inefficiency can create significant waste and cause a significant increase in energy bills.

What is soft water?

Essentially, soft water is the exact opposite of hard water. It has low mineral concentrations. Soft water can occur for a number of reasons including the water hasn’t flowed through any rocks or wells (i.e. rainwater), the rocks the water did flow through had very low concentrations of soluble minerals, or the minerals have been filtered out.

Due to some of the issues with hard water, there are individuals who choose to have systems that remove hard ions from their water. This is done through various mechanisms that will be described below. However, just as there are some issues with hard water, there are also some issues with water softeners.

Types of water softeners

  • Salt-based water softeners: Known as an ion exchange water softener, as it draws heavy minerals (like calcium and magnesium) into a resin within the softener, then releases sodium ions to complete the ion exchange process.
  • Salt-free water softeners: Utilize a template-assisted crystallization system to neutralize the minerals in water, rather than the ion exchange process of salt-based softeners.
  • Dual-tank water softeners: The tanks make it easier for the softener to manage a larger amount of heavy minerals, as well as a higher volume of water. These systems are designed with two resin tanks, allowing one tank to always remain functional, even while the other tank is going through a salt regeneration cycle.
  • Magnetic water softeners: These systems work as water descalers reduce the scale deposits (mineral buildup) that water passes through in your home's plumbing system. It works by neutralizing heavy minerals by stripping the negative or positive ions with a magnetic field.
  • Reverse osmosis water softeners: This system uses high pressure that forces water through a semipermeable membrane to filter minerals, metals, and nitrates from the water.
  • Shower head water softeners: Designed to remove minerals from shower heads by filtering the water as it passes through, typically in a salt-based design. Helps ensure the water you bathe in does not contain heavy minerals that can dry out your hair and skin while making it difficult to rinse away soap and shampoo.

Concerns with soft water

It eliminates health-preserving minerals: Minerals not only give water a characteristic taste, but they also supply a notable amount of health benefits. Research indicates that people receive anywhere from 5-20% of their daily calcium and magnesium intake from the water they drink. Removing any natural source of minerals in our often nutrient-bereft diets would be detrimental to health outcomes overall.  This will be discussed more in detail below.

Sodium and high blood pressure: As soft water replaces hard minerals like magnesium with soft ions like sodium, there is a concern for hypertensive people who may be susceptible to the blood pressure-raising effects of drinking water with higher sodium content. If you live in an area with very hard water or drink lots of tap water, the extra sodium can start to add up. It is well documented in research that significantly decreasing sodium consumption can lower blood pressure by up to 8mmHg [1].

Environmental burden: Traditional water softening systems discharge a significant amount of sodium and corrosive salt brine into municipal sewer lines, making it far more difficult for sanitation departments to clean and recycle the water. This is especially a problem in areas where there is a lot of agriculture requiring irrigation. In fact, may states have passed legislation banning these systems. In addition, many traditional softeners use a backwashing filtration pattern, resulting in wasting thousands of gallons of water per year.

Issues with distilled or osmotic water (soft water)

Distilled or osmotic water is an extreme of soft water. Sub-acute health effects can appear within weeks to months after starting regular consumption of distilled or demineralized water.

Signs and symptoms of profound deficiency of calcium, magnesium, or sodium are:

  • Extreme fatigue
  • Malaise
  • Nausea
  • Headache
  • Brittleness of nails and hairs
  • Leg and abdominal cramps
  • Preeclampsia
  • Twitch
  • Metabolic acidosis
  • Cardiovascular disorders (arrhythmia)
  • Higher diuresis [2]
  • Undesirable water quality

It is up for debate as to whether the amount of sodium (or possibly potassium) released into conventionally softened water is hazardous to health. Some experts caution against it, while others reply that there is not a large enough quantity to cause any real issue.

Oddly enough, most do agree that you should avoid watering your lawn and plants with softened water due to the harsh sodium content. To me, this is a convincing reason why not to use excessively soft water.

Health advantages of hard water

Drinking water with adequate levels of calcium and magnesium (i.e., hard water) has been repeatedly associated with a lower risk of cardiovascular mortality [3].

The hardness of drinking water is directly determined by the concentration of dissolved minerals, predominantly calcium, and magnesium, mainly in combination with bicarbonate, sulfate, and chloride. A comprehensive and systematic review of studies examining the apparent effects of soft water on cardiovascular disease and cancer was conducted in 2008 [4]. 

This review found evidence to support an inverse association between cardiovascular mortality and drinking water magnesium levels. In support of this finding, animal studies demonstrate that magnesium deficiency is associated with cardiac arrhythmias [5].

In addition, animal studies have shown that supplemental magnesium delivered via drinking water significantly improved the lipid profile and inhibited atherosclerosis [6].

In order to corroborate the previous indications of a protective relation of drinking water calcium and magnesium with cardiovascular disease, a recent population-based cohort study assessed the association of these minerals in drinking water with the incidence of myocardial infarction and stroke in postmenopausal women [7].

Drinking water with a high concentration of calcium and magnesium was associated with a reduced risk of stroke which seems to be primarily driven by magnesium.

Essentially, this data indicates that drinking water rich in calcium and magnesium, in particular magnesium, may lower the risk of stroke in postmenopausal women [7].

Ever since 1960, epidemiologic studies that were conducted in different countries by different researchers have consistently reported chronic health effects of naturally occurring low mineral water or artificially softened water (specifically water low in magnesium, calcium, or bicarbonates). 

A meta-analysis of 14 analytical observational studies (i.e. the most valid epidemiological studies) that investigated the association between cardiovascular disease and drinking water hardness found convincing evidence of the protective role of magnesium in drinking water. The highest exposure category (people consuming drinking water with a magnesium content of 8.3–19.4 mg/l) was significantly associated with a decreased likelihood of cardiovascular mortality by 25% compared with people consuming water with a magnesium content of 2.5–8.2 mg/l [4].

Two recent and independent meta-analyses that considered several more recent studies reportedsimilar results [8].

The current position of the World Health Organization is that the strength of evidence is insufficient to propose guidelines for calcium, magnesium, or water hardness.

There is other evidence that indicates a protective or beneficial effect of water calcium and magnesium is associated with other chronic diseases including neurological disturbances, amyotrophic lateral sclerosis, preeclampsia in pregnant women, high blood pressure, and metabolic syndrome [9].

Lack of calcium or magnesium in drinking water seems to cause lower bone mass density, higher incidence of fractures, and disturbed bone development in children [10]. 

In addition, a recent review showed that six epidemiological studies in Taiwan and Slovakia reported that water hardness and magnesium were associated with lower cancer risks [9].

Mechanisms on how hard water enhances health

  • There are numerous biologically plausible mechanisms by which drinking water magnesium may exert protective effects on the brain. Magnesium possesses vasodilatory, anti-inflammatory, anti-ischemic, and antiarrhythmic properties [11].
  • Magnesium supplementation significantly lowered blood pressure in adults [12], and high blood pressure is a strong risk factor for stroke. The bioavailability of magnesium has been suggested to be higher in drinking water than that in food [13].
  • There seems to be a stronger association of drinking water magnesium with ischemic stroke that is observed among those with a low dietary magnesium intake.

Potential benefits of higher pH water

Essentially, more magnesium and calcium in water increases the pH. There’s evidence that higher pH water, that is pH of water that tends to be somewhere between high sevens (i.e., ~7.9 to 9) is going to be more readily absorbed and is going to more favorably impact the function of our cells than lower pH water [14].

If the levels of tap water are essentially between 8.3 to 19.4 mg/L of water, chances are that you don’t need to enhance the pH of that water or change its magnesium concentration. If the levels are less than 8.3 mg/L of magnesium, then this can potentially cause the pH to be too low that it will not cause some of the favorable health components that higher pH water can.

These results may potentially be used for guiding recommendations on magnesium in drinking water and be an incentive for adding minerals to drinking water with otherwise low concentrations such as filtered or desalinated drinking water. 


Very hard water may be partially softened to prevent scaling or an unpleasant taste without an adverse health risk. However, there may be health benefits that are lost with the removal of calcium, magnesium, and other minerals, and it may be practicable to require keeping some minimum level of these and other essential elements in the treated water. Additionally, it’s quite difficult and may not be feasible to substantially increase the naturally low content of calcium and magnesium in drinking water.

Desalination and softening of drinking water significantly remove minerals that offer health benefits.

Because these processes are increasingly being used, it is important to consider whether desalinated and softened water should have minimum levels of essential elements such as magnesium and calcium to improve taste and provide health benefits.

National administrations can protect public health from this emerging risk, and international bodies and organizations dealing with drinking water safety and quality should develop guidelines based on the most recent epidemiological knowledge and precautionary principles.

Staying hydrated is key to your health, and knowing what type of water you are drinking is another piece of the puzzle!

1.    Montasser, M.E., et al., Determinants of blood pressure response to low-salt intake in a healthy adult population. J Clin Hypertens (Greenwich), 2011. 13(11): p. 795-800.
2.    Kozisek, F., Health risks from drinking demineralized water, in Nutrients in Drinking Water. 2005, WHO: Geneva. p. 148-163.
3.    Rubenowitz, E., et al., Magnesium in drinking water in relation to morbidity and mortality from acute myocardial infarction. Epidemiology, 2000. 11(4): p. 416-21.
4.    Catling, L.A., et al., A systematic review of analytical observational studies investigating the association between cardiovascular disease and drinking water hardness. J Water Health, 2008. 6(4): p. 433-42.
5.    Anderson, T.W., et al., Ischemic heart disease and elements in water. Can Med Assoc J, 1975. 113(10): p. 925.
6.    Cohen, H., et al., Atherogenesis inhibition induced by magnesium-chloride fortification of drinking water. Biol Trace Elem Res, 2002. 90(1-3): p. 251-9.
7.    Helte, E., et al., Calcium and magnesium in drinking water and risk of myocardial infarction and stroke-a population-based cohort study. Am J Clin Nutr, 2022. 116(4): p. 1091-1100.
8.    Kozisek, F., Regulations for calcium, magnesium or hardness in drinking water in the European Union member states. Regul Toxicol Pharmacol, 2020. 112: p. 104589.
9.    Rosborg, F.K.E., Drinking Water Minerals and Mineral Balance. 2020, Springer International Publishing: London.
10.    Huang, Y., et al., Low-mineral direct drinking water in school may retard height growth and increase dental caries in schoolchildren in China. Environ Int, 2018. 115: p. 104-109.
11.    Kolte, D., et al., Role of magnesium in cardiovascular diseases. Cardiol Rev, 2014. 22(4): p. 182-92.
12.    Zhang, X., et al., Effects of Magnesium Supplementation on Blood Pressure: A Meta-Analysis of Randomized Double-Blind Placebo-Controlled Trials. Hypertension, 2016. 68(2): p. 324-33.
13.    Barbagallo, M., N. Veronese, and L.J. Dominguez, Magnesium in Aging, Health and Diseases. Nutrients, 2021. 13(2).
14.    Chycki, J., et al., The effect of mineral-based alkaline water on hydration status and the metabolic response to short-term anaerobic exercise. Biol Sport, 2017. 34(3): p. 255-261.
15.    Sim, M., et al., Hydrogen-rich water reduces inflammatory responses and prevents apoptosis of peripheral blood cells in healthy adults: a randomized, double-blind, controlled trial. Sci Rep, 2020. 10(1): p. 12130.

Dr. Paul Henning

About Dr. Paul

I'm currently an Army officer on active duty with over 15 years of experience and also run my own health and wellness business. The majority of my career in the military has focused on enhancing Warfighter health and performance. I am passionate about helping people enhance all aspects of their lives through health and wellness. Learn more about me