Hot springs are known around the world, and for thousands of years, people have visited them in search of healing and rejuvenation. From the foggy mountain hot springs in Japan to the marble-tiled Roman baths, it has been recognized that hot springs are considered the "nature's medicine", relaxing, restoring, and healing.

These geothermal delights have given rise to tales, rituals, and perhaps an introduction to wellness tourism.   

But, as the modern traveler may drink, bathe in, and bottle this so-called "miracle water", one vital question arises: Can we drink hot spring water safely?

We will cover the cultural background of the mineral water tradition, as well as the latest scientific studies on its curative properties and safe drinking practices. We will also examine the potential hazards of unfiltered sources and compare them with hot spring water and other systems that use filters to ensure the purity of the minerals and balance. 

Since natural is not necessarily safe, it is essential to know the truth about hot spring water so one can make healthier, more informed choices.

A Cultural and Historical Look at Hot Springs

Before science could explain the process of geothermal activity, ancient peoples viewed hot springs as blessings from the gods and considered them places where God breathed into the Earth, acting as a curer of diseases. 

Such natural baths evolved into places of spirituality, health, and community life, as well as places that linked people with the power of nature and with one another.

Japan: The Onsen Tradition

In Japan, onsens have been an integral part of everyday life and health for over a millennium. A volcano fed these mineral-rich baths, and it was believed to cleanse both the body and spirit.

Historical texts depict warriors returning to the onsen to refresh after a battle, and the monks viewed it as a means to bathe themselves and practice meditation. Every onsen area has its legend: gods sanctified some springs, others healed wounded animals, and they are so firmly integrated into Japanese culture.

In modern times, the existence of onsens continues to underpin health tourism and social connectivity.

Rome: Baths of the Elite and the Everyday

Bathing was a social and ritualized practice among the Romans. The great thermae of Caracalla and Diocletian were beautiful places where people could gather not only to take a bath but also to discuss various issues, engage in physical exercise, and receive medical treatment. 

Roman doctors prescribed the use of hot and cold baths to treat arthritis, anxiety, and several other illnesses. Their excellent engineering allowed the even thermal waters to be diverted by the aqueducts, and this, coupled with the fact that they were able to divert even the thermal waters through the aqueducts, meant that "taking the waters" was a daily luxury throughout the entire empire.

Europe: The Era of the "Drinking Cure"

The change to mineral water became a symbol of 18th and 19th-century European spa culture. Elite health retreats were found in French cities such as Vichy, German towns such as Baden-Baden, and English cities such as Bath. 

Physicians, along with aristocrats, promoted the so-called drinking cure, which involved taking moderate doses of mineral water believed to cleanse the inner organs and balance the humors. Such Spa towns flourished, a combination of medicine, social status, and recreation—the earliest forms of what we today call wellness tourism.

Indigenous and Local Traditions

Indigenous people outside Europe and Asia also held Geothermal waters in high esteem. The Native Americans believed that hot springs were regenerative and harmonious places where leaders and healers could perform purification practices.

The Māori people also believed in the geothermal pools in New Zealand, using them for cooking, curing, and bathing in communal areas, and regarding the warm Earth as a manifestation of their ancestors.

Similarly, settlers in Iceland employed therapeutic pools as a survival strategy to withstand harsh winters, and they became a basic community institution. Hot springs are one of the symbols that have been used across continents and centuries to demonstrate how the Earth, water, and well-being are in harmony, serving as a reminder that people have long relied on the wisdom of nature to heal them.

However, although our forefathers worshipped these so-called "miracle waters", they had no idea that a lurking danger lay beneath the surface of the waters they thought so warm. It was not until modern science developed a proper understanding of the problem that it could grasp the full extent of the danger.

What's in Hot Spring Water? Understanding Its Unique Composition

Hot springs are natural, mineral-rich features formed when water flows through layers of rock and soil heated by Earth's geothermal activity. Every spring has a unique mineral character and a distinct therapeutic quality.

The following is a list of some of the minerals that are commonly found in natural hot springs and the types of minerals they are composed of:

Hot springs are not all of high quality, even though some can be beneficial to health at moderate, safe concentrations. Some of them may contain toxic metals such as arsenic, mercury, or lead, depending on the local geology and volcanic activity. These pollutants can accumulate in the body over time, leading to severe health conditions.

Consumers tend to believe that mineral water is healthy, and it is essential to keep in mind that the earth never filters pollutants; it concentrates them. The distinction is in regulation and purification.

Are There Real Health Benefits to Drinking Mineral Waters?

Recent studies have aimed to verify what ancient humankind had always known: mineral water is not only able to quench thirst, but it may also be helpful. Despite the few verified factual benefits, these impacts are highly influenced by the content and purity of the minerals, as well as the consistent use of safe sources.

Hydration and Electrolyte Balance 

According to a study published in the Journal of Water and Health (World Health Organization), hydration and electrolyte replenishment with naturally mineralized water are more effective than with demineralized water. Calcium, magnesium, and potassium are essential minerals for muscle contraction, nerve conduction, and maintaining fluid balance in the body. They are significant for athletes and individuals living in hot climates.

According to the recommendations of the National Institutes of Health (NIH), magnesium-rich fluids can help improve performance and reduce fatigue in athletes because they do not lead to cellular dehydration.

This goes hand in hand with the idea that not all hydration sources are created equal—water containing large amounts of electrolytes will help much more in maintaining and recovering energy than distilled or purified water alone. 

Digestive Health and Bicarbonate Effects

High-concentration mineral waters with bicarbonates have been the subject of numerous studies on their effects on the digestive system and acid control. Research published in the European Journal of Gastroenterology and Hepatology suggests that excess stomach acid can be countered by drinking water with bicarbonate, which may help reduce acid reflux, dyspepsia, and heartburn.

Bicarbonate is a natural antacid that helps stabilize stomach pH, making digestion easier. A controlled trial published in the World Journal of Gastroenterology found that bicarbonate-containing waters may increase gastric emptying and intestinal motility. It can thus be used to treat moderate digestive disorders in humans.

Bone and Heart Health

The World Health Organization (WHO) acknowledges that the daily intake of minerals may be significantly affected by the levels of calcium and magnesium in drinking water. As has been testified by numerous researchers, the following statement is true:

• According to a study published in the Osteoporosis International Journal, women who consumed calcium-enriched mineral water daily had higher bone mineral density and better calcium intake than those who took calcium supplements.

• Another study, published in the American Journal of Clinical Nutrition, found that magnesium in mineral water helps normalize heart and blood pressure, thereby maintaining a normal heart rhythm. 

The consistent use of mineral water containing optimal levels of calcium and magnesium can help prevent the development of bone and heart disease, particularly in populations with low levels of these minerals.

Metabolic and Detoxification Effects

Recent studies discuss the effects of mineral waters on metabolism. A 2022 review published in the journal Nutrients (MDPI) found that silica- and bicarbonate-containing waters can support natural detoxification by enhancing kidney function and toxin removal. Other studies have attributed lithium distribution in mineral waters to mood stabilization and reduced oxidative stress, but at low, controlled concentrations.   

Balance and Safety Matter

Although the advantages are evident, researchers always emphasize one key condition: the source must be pure. Excess of minerals or heavy metal poisoning can nullify any form of therapeutic effect.

The very water that aids in the digestion of food or the solidity of bones might be a toxin when it contains arsenic, lead, or disease-causing bacteria, which are frequently present in untested water or even geothermal water.

In short, modern science verifies some of the ancient wisdom:

Mineral water may support hydration, enhance digestion, support bone health, and aid heart function. The trick is balance and safety; however, pure, controlled mineral waters or filtering options can be beneficial and risk-free.

Which Hot Springs Are Safe to Drink — and Which Are Not

Hot spring waters are not created equal. The majority of those are safe to bathe in, and only a minor portion is safe to drink. The significant variations involve temperature, mineral content, bacterial activity, and regulatory control.

Safe Sources: Bottled and Regulated Mineral Waters

Geothermal areas like San Pellegrino (Italy), Vichy Celestins (France), or Hakone Onsen Water (Japan) have no issues with distributed commercial mineral water, as it is treated, tested, and monitored.

These waters are filtered and then microbiologically tested to remove harmful organisms and restore mineral balance before being bottled. They must comply with the World Health Organization (WHO) and local potable water standards.

This not only reduces the risk of contamination for consumers but also provides them with valuable minerals, including calcium, magnesium, and bicarbonate. In essence, bottled mineral water is nothing more than controlled, protected natural spring water.

Unsafe Sources: Unregulated or Wild Hot Springs

Magma heats the groundwater to extremely high temperatures, causing the minerals in the surrounding rock to dissolve. However, it contains heavy metals, namely arsenic, lead, and mercury.

In addition, warm bodies of water provide a perfect habitat for bacteria and amoebas, especially in shallow water. 

One example is Yellowstone National Park in the U.S. and the Beppu hot springs in Japan, which also feature crystal-clear pools, but the water cannot be used for drinking.

In such parks, authorities have posted signs warning visitors not to drink from or open wounds in a given spring, as it poses microbial and chemical hazards.

Red Flags That a Spring Is Not Safe to Drink

• The odor of rotten eggs is a sure sign that hydrogen sulfide is present; this highly toxic gas is especially dangerous when inhaled in large amounts.

• The suspended minerals, algae, or activity of bacteria may occur in the form of cloudy or colored water.

• It also lacks any markings or regional warnings that it is drinkable.

• Their proximity to factories, volcanoes, or mines makes them particularly prone to contamination.

• Hot water (greater than 60 °C / 140 °F), which could contain concentrated minerals or gases that are harmful to swallow.

This apparently innocent spring could be hiding something harmful. Being clear does not mean being clean, and experts often emphasize this point.

Tip: It is good practice never to ignore warning signs, and if in doubt, never drink untested or untreated geothermal or spring water. On the safe side, the safest options are mineral-balanced hydration, controlled bottled mineral water, or high-quality filters.

When "Natural" Isn't Necessarily Safe

When water is expelled from the Earth, it is believed to be pure. Unfortunately, nature does not always clean itself.

Heavy Metal Contamination

Geothermal activity typically leaches arsenic, lead, mercury, and fluoride from the surrounding rocks into the environment. They are capable of resulting in repeated exposure, which can result in:

• Mercury causes neurological impairment.

• Kidney and cardiovascular disease (from lead)

• Cancer (from arsenic)

• Bone and dental problems (due to the elevated fluoride levels).

In 2023, researchers in the Environmental Geochemistry and Health Journal found that some Asian hot springs contain arsenic levels that are extremely dangerous, well above the WHO drinking water limit.  

Bacterial and Microbial Threats

Mineral-saturated, warm conditions are also conducive to microbial growth. Many untreated springs worldwide have been found to contain pathogens, such as Legionella and Naegleria fowleri (the so-called "brain-eating amoeba"). With a single swallow, you can contract a severe disease or infection.

Excess Mineral Load

Even the absence of bacteria or metals in some springs does not imply that they do not contain high amounts of sodium, sulfur, or bicarbonates; this may not be healthy for individuals with high blood pressure, kidney disease, or digestive sensitivities.

Hot springs are thus very nice to take a bath in; however, taking them without treatment will expose you to more harm than good.

Hot Spring Water vs. Filtered Water: Which Is Safer to Drink?

After discussing the potential harm of untreated spring water, the question arises: What about the water we drink every day at home? Hot springs may contain natural minerals, but they can also be hazardous.

Modern filtration, on the other hand, is scientifically grounded in terms of uniformity and regulation. It is best to have hot spring water and filtered water next to each other, so it is easy to see which one is more purifying and health-beneficial.

Let's break it down clearly:

On the one hand, the new generation of home filtration systems, such as the Berkey, is designed to offer the best of both worlds: safe and mineral-rich water that is also steady and sustainable.

Berkey's filters remove:

• Pathogens (bacteria, viruses, parasites)

• Heavy metals (mercury, arsenic, and lead)

• Chemicals and microplastics, chlorine.

However, they still contain valuable minerals, and your drinking water will keep you healthy without the dangers of untreated water. It is a modern redefinition of the purity of nature, actually, one that utilizes the help of science.

Eco and Health Perspective: Sustainable Hydration Choices

When selecting the drinking water you consume daily, health is not the only consideration; environmental factors also play a role. Although bottled mineral water is a convenient and affordable option, its ecological impact reveals a different story.

Since the extraction of natural resources, manufacturing, and the discarding of plastic bottles, the planet has paid a much higher price than most people might believe. 

The Hidden Cost of Bottled Water

It is estimated that millions of plastic bottles are thrown in landfills or the sea every year, which is one of the causes of the global plastic pollution crisis. The United Nations Environment Programme (UNEP) has found that less than 10% of all plastic produced is recycled. The remainder remains in the ecosystems for centuries.

In addition to waste, the bottling and transportation of water to different regions consume massive volumes of fossil fuel, emitting tons of carbon. Even extracting spring water can weaken fragile ecosystems, affecting both local people and wildlife.

Filtered Water: A Greener, Smarter Alternative

Home filtration systems, on the other hand, offer a long-term solution for hydration that benefits not only the body but also the environment. The systems, including the Berkey, can also be refilled with your personal tap water, reducing significant plastic waste and transportation emissions.

Why Filtered Water Is the Eco-Friendly Choice:

• Reduced Plastic Waste: A single Berkey filter can replace thousands of bottles that would otherwise be discarded.

• Energy Saving: The industry has no requirements for bottling, shipments, or packaging.

• Long-Term Savings: Filters can filter thousands of liters of water, saving both money and water.

• Assured Quality Everywhere: The water filter ensures drinkable water, both in urban areas and off-grid.

Filtering will enable you to make a healthier and more sustainable decision. By refusing to drink bottled water and instead filtering water, you will not only protect your health but also the future of the planet. The planet does not require clean water produced at high cost and with expensive filters, such as those from Berkey. 

Natural Doesn't Always Mean Safe

From the divine onsens of Japan to the thermal spas of Europe, hot spring water has delighted humans and been used for meditation for centuries. It is mineral-enriched and gently heats the body, providing complete relaxation, and may even be beneficial to the skin. This is not to say that one can drink directly from the source, though. 

What science cannot tell us today is illustrated by custom: it is the testing, treatment, and regulation of purity, not nature, which establishes it. Natural hot springs remain one of the best ways to relax and maintain a healthy state of mind.

Nevertheless, toxic metals, bacteria, and excess minerals can contaminate untreated geothermal water, causing severe health effects when ingested. The filtered water is a cheaper, safer, and less harmful alternative to tap water as a daily source of hydration.

The latest filtration system provides crystal-clear water, free from contaminating elements, with all the mineral benefits of nature, enhanced by technology.

Do not be a humper of what the hot springs of the world are, get them, leave them as they are; beautiful, natural baths which soften your flesh, may help with skin conditions,  and clear your mind.

However, when it comes to what you eat daily, filter through fiction instead of reality. Purity is no longer always synonymous with safety in the modern world, though clean, filtered water is generally safe.

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