What Exactly Is Distilled Water?

You’ve probably faced this choice while dining out: Tap, bottled, or sparkling water?

But what about distilled water?

It’s not that different from what flows out of your kitchen faucet. But distilled water goes through a process that sets it apart from other types of H2O.

How It’s Made

Some people claim that it’s the purest water you can drink. All water -- no matter if it comes from a natural spring, artesian well, or regular tap -- may have trace but safe amounts of minerals, bacteria, pesticides, and other contaminants.

Distilling rids the water of all those impurities. Distilled water is steam from boiling water that’s been cooled and returned to its liquid state. Distilling also removes more than 99.9% of the minerals dissolved in water.

Taste

Distilled water is safe to drink. But you’ll probably find it flat or bland. That’s because it’s stripped of important minerals like calcium, sodium, and magnesium that give tap water its familiar flavor. What’s left is just hydrogen and oxygen and nothing else.

Uses

Distilled water is ideal for when purity is important. Common uses include:

Medical tools and procedures. Hospitals clean equipment with it to help avoid contamination and infections. Kidney dialysis machines use ultra-pure water to filter waste from blood.

Lab tests. Nothing in distilled water reacts with or affects the accuracy of lab experiments.

Cosmetics. If water is an ingredient in your moisturizer, deodorant, or shampoo, it’s almost always distilled.

Automobiles. Since it lacks minerals, distilled water won’t corrode metal engine parts or interfere with batteries.

At home, you may want to reach for distilled water for cooking and several other reasons, including to:

  • Mix it with infant formula if your baby has weak immunity. Otherwise, tap water is fine.
  • Fill the water chamber for a CPAP humidifier if you use it for sleep apnea. Many manufacturers recommend distilled water to make the humidifier last longer.
  • Use it with a neti pot to clear your sinuses.
  • Use it in your clothes iron to help prevent scale buildup.
  • Shampoo your hair. Fluoride, chlorine, and other additives in the water from your shower may dull your tresses.

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What to Watch For

Remember that distilled water lacks even electrolytes like potassium and other minerals your body needs. So you may miss out on a bit of these micronutrients if you drink only the distilled stuff.

Some studies have found a link between drinking water low in calcium and magnesium to tiredness, muscle cramps, weakness, and heart disease. Also, distilled water may not help you stay hydrated as well as other kinds of water.

If you use distilled water for your fish tank, be sure to add a sea minerals supplement to the aquarium. Some coffee fans think that distilled water makes for a purer-tasting cup. But the Specialty Coffee Association of America says that a certain level of minerals is ideal in order to extract the best brew.

Storage

Unopened bottled distilled water from a store lasts basically forever. But stash it away from direct sunlight. And once it’s opened, be sure to close it up well after use. Certain germs can grow even in nutrient-poor distilled water.

WebMD Medical Reference Reviewed by Kathleen M. Zelman, MPH, RD, LD on July 12, 2019

Sources

SOURCES:

U.S. Environmental Protection Agency: “Water Health Series.”

University of Georgia Extension: “Water Quality and Common Treatments for Private Drinking Water Systems.”

International Bottled Water Association: “Types of Water -- Bottled.”

Stanford Magazine: “Don't Drink the Water (From Your Dehumidifier): Nitty-Gritty.”

CDC: “Healthy Water: Medical and Dental Equipment,” “Healthy Water: Water Use in Hemodialysis,” “Background D. Water.”

Cosmeticsinfo.org: “Find an Ingredient: Water.”

Distilled Water Association: “Using Distilled Water For Your Fish Tanks: How to Make It Safe.”

The Distilled Water Company (UK): “How Long Does Distilled Water Last? Shelf Life & Storage Uncovered.”
Word Health Organization: “Health Risks from Drinking Demineralized Water.” 

Journal of General Internal Medicine: “Comparison of the Mineral Content of Tap Water and Bottled Waters.”

Seattle Children’s: “Bottle-Feeding (Formula) Questions.”

Nutrients (Switzerland): “Impact of Isotonic Beverage on the Hydration Status of Healthy Chinese Adults in Air-Conditioned Environment.”

Specialty Coffee Association of America: “Water for Brewing Standards.”

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