Why the purest water is not necessarily the healthiest to drink

Food & Drink · Published 2 October 2026 Swipe more like this →

In short: Distilled water is stripped of almost every mineral, leaving a liquid so pure it can even corrode car engines. While this purity prevents limescale in your iron, it lacks the essential nutrients found in hard water that may actually protect your heart.

Distillation is a purification process that involves boiling water into vapor and condensing it back into a liquid in a separate container. This mechanism effectively leaves behind non-volatile impurities, such as minerals and metals, in the original vessel. In commercial settings, this process can reduce the total dissolved solids to less than 1 part per million, significantly lowering electrical conductivity compared to typical tap water, which ranges from 200 to 800 μS/cm.

While the extreme purity of distilled water is beneficial for sensitive machinery—such as preventing scale in steam irons, humidifiers, or CPAP machines—it is not a nutritional panacea. There is no proven health advantage to drinking distilled water over hard water. In fact, some research suggests that the minerals found in hard water, such as magnesium and calcium, may offer cardiovascular benefits. For instance, the American Journal of Esidemiology has noted a negative correlation between hard water consumption and atherosclerotic heart disease.

The chemistry of distilled water is also surprisingly reactive. Because it lacks mineral buffers, it tends to absorb carbon dioxide from the atmosphere, forming a weak carbonic acid that drops the pH to approximately 5.8. This lack of ions can also be problematic in other contexts; for example, the ions present in tap water can drastically reduce the lifespan of lead-acid car batteries. Conversely, in specialized uses like early Boeing 707 engines, the use of distilled water helped increase air density to assist with takeoff in hot, high-altitude conditions.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• Is bottled mineral water actually healthier than the water flowing from your kitchen tap?
• Pure water is a surprisingly poor conductor of electricity, unlike the water we drink.
• Why your water's mineral content matters more for fish than for your morning glass.
• Why your glass of water is a complex chemical equilibrium, not just H2O
• Water is more than a liquid; it is a structural architect of the physical world.
• Donburi is the ultimate Japanese comfort food, transforming simple leftovers into a complete meal.
• Low-fat and low-carb diets tie when calories match
• The dosa is at least a thousand years old and still argued over
• Dessert once meant clearing the table, not cake
• Dough is more than just flour and water; it is a complex physical structure.
• For two centuries, this tiny artificial island was Japan's only window to the West.
• From ancient survival to culinary icon, drying fish is the world's oldest preservation method.

More in Cooking, food and drink · More in Food & Drink · Latest · A–Z · All topics