Is it safe to drink boiled distilled water?

December 24, 2025 •

4 min read

While boiling is an effective way to kill pathogens in tap water, the process is redundant for distilled water, which has already undergone purification. Most commercially available distilled water is already sterile, meaning reheating it offers no additional safety benefit and may pose certain risks if not handled correctly.

Quick Summary

Boiling distilled water is unnecessary for safety as it is already highly pure; however, it is not inherently unsafe to do so. The main concerns with consuming distilled water, whether boiled or not, relate to its lack of minerals and electrolytes, which can potentially impact the body's hydration and nutrient balance over time.

Key Points

Boiling is Unnecessary for Distilled Water: Since distillation already removes microorganisms, re-boiling distilled water provides no additional safety benefits.
Distilled Water Lacks Essential Minerals: The distillation process strips water of important minerals like calcium and magnesium, which are vital for bodily functions.
Long-term Consumption Can Cause Issues: Relying solely on distilled water can potentially lead to electrolyte imbalances, increased urination, and mineral deficiencies over time.
Taste is a Drawback: The absence of minerals gives distilled water a flat, bland taste, which may discourage adequate water consumption.
Use for Specific Purposes Only: Distilled water is ideal for medical equipment (CPAP machines), labs, and appliances where mineral-free water is required to prevent buildup.
Distilled Water is a Potent Solvent: Its purity means it can leach trace amounts of chemicals from storage containers; use glass or high-quality plastic for safety.

Understanding Distilled Water and the Effects of Boiling

Distilled water is created by boiling water into steam and then condensing the vapor back into a clean liquid, a process that removes 99.9% of dissolved solids, minerals, and contaminants. In a laboratory or medical setting, this extreme purity is beneficial for processes that require a completely mineral-free liquid. For drinking purposes, however, this very purity creates its own set of considerations.

Boiling, in contrast, is primarily a disinfection method that heats water to kill microorganisms like bacteria and viruses. When you boil distilled water, you are essentially reheating a product that is already free of these pathogens. This action does not introduce any new contaminants unless the boiling vessel itself is dirty. The real health questions, therefore, are not about whether the act of boiling is safe, but whether consuming demineralized water in general is healthy in the long term.

The Impact of Mineral Depletion on the Body

The most significant health consideration when drinking boiled distilled water is the absence of essential minerals. Unlike tap or spring water, which contain trace amounts of electrolytes such as calcium, magnesium, and potassium, distilled water is devoid of these substances. While most people get the majority of their minerals from food, relying solely on distilled water can be problematic, especially for individuals with compromised diets or health issues. The World Health Organization (WHO) has noted potential adverse effects associated with long-term consumption of demineralized water, primarily linked to this mineral absence.

Potential risks associated with a lack of minerals in drinking water include:

Electrolyte Imbalance: Minerals play a crucial role in maintaining the body's fluid balance. Their absence in distilled water can disrupt this, potentially leading to symptoms like headaches, weakness, and muscle cramps.
Increased Urine Output: Studies cited by the WHO found that drinking pure, low-mineral water can increase urine production by about 20%, which may heighten the risk of dehydration.
Metabolic Issues: Some research suggests a decrease in metabolic function associated with a lack of minerals in water, though more evidence is needed.
Altered Taste: Many people find the taste of distilled water flat or bland due to the lack of dissolved minerals, which can lead to drinking less water overall.

Comparing Drinking Water Types: Boiled Distilled vs. Filtered vs. Tap

To illustrate the differences, consider this comparison:


Feature	Boiled Distilled Water	Filtered Tap Water	Regular Tap Water
Mineral Content	Essentially none; completely demineralized.	Retains beneficial minerals, depending on the filter type (e.g., carbon, some RO).	Contains natural minerals, but levels vary by source.
:---	:---	:---	:---
Purity	Highest purity, free of microorganisms, minerals, and dissolved solids.	High purity, removes many contaminants and unpleasant tastes/odors.	Purity varies; typically treated but can contain trace contaminants.
Taste	Flat and bland due to lack of minerals.	Often improved taste from removal of chlorine and other compounds.	Taste can vary greatly depending on the local water source.
Best For	Medical equipment, CPAP machines, appliances, short-term drinking if needed.	Daily drinking, cooking, general household use.	Safe for daily use in many areas, but purity is lower.
Considerations	Not ideal for long-term hydration due to lack of minerals.	Requires filter maintenance; cost varies by filter type.	May contain trace contaminants or residual treatment chemicals.

When is Boiled Distilled Water Necessary?

While not the best choice for everyday hydration, boiled distilled water is useful in specific, targeted scenarios. These applications typically involve sensitive equipment or medical procedures where the absence of minerals and other solids is critical.

CPAP Machines: Distilled water prevents mineral buildup in the humidification chamber, ensuring the device functions properly.
Medical Sterilization: Hospitals and labs use distilled water to prevent spotting and corrosion on surgical instruments.
Laboratory Work: Experiments that require a pure solvent depend on distilled water to avoid contamination.
Baby Formula (in specific cases): Some pediatricians may recommend it, particularly if the local water source is of questionable quality.

The Aggressive Nature of Distilled Water

Due to its purity and lack of dissolved substances, distilled water is a more aggressive solvent than regular tap water. This means it can readily absorb trace amounts of chemicals and minerals from its surroundings, including the container it is stored in. For this reason, it is always recommended to store distilled water in non-reactive containers, such as glass or high-quality BPA-free plastic, to prevent it from leaching potentially harmful substances from the material.

Conclusion: The Bottom Line on Safety

Drinking boiled distilled water is not dangerous in the short term, assuming a balanced diet provides sufficient minerals. However, the act of boiling it is redundant and adds no further safety. The main drawback is the lack of essential minerals, which are crucial for proper bodily function. For regular, long-term hydration, health experts generally recommend tap water (if safe), filtered water, or remineralized purified water, which provide both hydration and a valuable source of dietary minerals. Ultimately, a conscious awareness of your mineral intake from all sources is key to a healthy hydration strategy. For specific medical questions, consulting a healthcare professional is always the best course of action.

World Health Organization information on health risks of demineralized water

Frequently Asked Questions

No, it is not inherently dangerous to drink boiled distilled water in the short term. However, boiling distilled water is unnecessary for safety, as the distillation process already makes it free of pathogens.

Boiling distilled water does not make it safer for consumption. Distillation removes all harmful microorganisms, so reheating it serves no purpose from a safety standpoint.

People advise against drinking distilled water regularly because it lacks essential minerals and electrolytes like calcium and magnesium. Relying on it as your sole source of hydration over the long term can lead to nutritional deficiencies and health complications.

No, you should not use boiled tap water in a CPAP machine. While boiling kills pathogens, it does not remove minerals. These minerals will cause limescale buildup and damage the machine over time.

This is a common misconception. While distilled water is an aggressive solvent, the body's natural mechanisms regulate mineral balance. It will not actively pull minerals from your bones or tissues, though it does not contribute any minerals, so you must get them from your diet.

Boiled water is heated to kill germs but retains all its minerals and impurities. Distilled water is created by boiling and condensing steam, which removes both microbes and minerals, making it extremely pure.

Drinking a very large quantity of any water can be dangerous, but with distilled water, there is an increased risk of overhydration and electrolyte imbalance due to its lack of minerals. In extreme cases, this can lead to water intoxication.