Distilled water is about as pure as water gets. Boil it into steam, catch that steam on a cold surface, and it drips back as liquid with almost all of its minerals, bacteria, and dissolved contaminants left behind in the pot. Store shelves stock it by the gallon, but you can make a batch at home for the cost of running your stove.
That is worth knowing when the shelves are empty, when you are off-grid or camping, or when a CPAP machine or car battery needs mineral-free water and you have run out. The gear is already in your kitchen: a pot, a lid, a bowl, and some ice.
Below you will find what distilled water is actually good for, three ways to make it yourself, and how to store it so it stays pure.
Key Takeaways
- Distilled water is water boiled into steam and condensed back to liquid, which leaves nearly all minerals, bacteria, and dissolved contaminants behind.
- It is the right pick for CPAP machines, humidifiers, steam irons, and lead-acid car batteries, where tap water minerals cause scale, clogs, and corrosion.
- You can distill water at home with a pot, a lid, a bowl, and ice using the pot-and-bowl method in about 45 minutes.
- Store distilled water in a sealed glass or food-grade plastic container in a cool, dark spot to keep it pure.
Common Uses for Distilled Water
Most people know distilled water is pure, but its lack of minerals makes it specifically useful for machinery and medical needs. Distilling water creates a blank slate. You boil water into gas and condense it back to liquid, leaving heavy impurities behind.
This process makes it safe to drink, but it tastes flat. Since it lacks minerals like calcium and magnesium, it’s not the best daily water source for hydration. However, that lack of minerals is exactly why it is perfect for the following applications:
Medical Equipment
Hospitals rely on distilled water to prevent infection and cross-contamination. Its sterility matters for several tasks:
- Sterilizing instruments: Doctors use it to clean tools without leaving mineral deposits or residue.
- Cleaning wounds: It prevents bacteria from entering open cuts during cleaning or surgery.
- Scrubbing in: Surgeons rinse with it after washing to ensure no tap-water bacteria lingers on their skin.
- Dental work: Dentists use it to rinse mouths after extractions to keep the area sterile.
CPAP Machines
If you use a Continuous Positive Airway Pressure (CPAP) machine for sleep apnea, distilled water is non-negotiable.
Many CPAP units have humidifiers to prevent dry mouth (1). Tap water contains minerals that build up inside the reservoir and hose. This scale buildup can breed bacteria and ruin the machine. Distilled water keeps the air you breathe clean and your machine running smoothly.
Household Humidifiers
Just like with CPAP machines, standard humidifiers last longer with distilled water. Tap water often leaves a fine white dust (mineral residue) on furniture around the room. It also leads to hard crusty deposits inside the tank.
Keep In Mind
Steam Irons
Tap water is hard on a steam iron. The minerals eventually clog the steam vents, causing the iron to spit white chalky bits onto your fresh clothes. Distilled water prevents these clogs and extends the life of your appliance.
Automotive Maintenance
Your car loves distilled water. Minerals found in tap water can corrode metal parts and interfere with chemical reactions. It is commonly used for:
- Lead-acid batteries: Topping off batteries requires pure water to facilitate the flow of electricity.
- Cooling systems: Mixing coolant with distilled water prevents mineral scale from blocking the radiator.
Aquariums
Fish enthusiasts often use distilled water to have total control over their tank’s chemistry. Since it has no minerals or chemicals, owners can add specific supplements to create the perfect environment for sensitive fish or coral.
Cosmetics and Canning
If you check your lotion bottles, you will likely see distilled water listed. It prevents bacteria growth in the product. Similarly, canning fruits and veggies with distilled water helps the color and flavor stay true, since there are no minerals to alter the taste.
Understanding the pH of Distilled Water
Ideally, distilled water is neutral with a pH of 7 immediately after the process.
However, it is highly sensitive. Once exposed to air, it absorbs carbon dioxide, which reacts to form a small amount of carbonic acid (2). Within about two hours of exposure to fresh air, the pH can drop to around 5.8. This is essentially harmless but worth knowing if you are testing water acidity.
How to Store Distilled Water Properly
You went through the trouble of making pure water, so don’t ruin it with bad storage. Follow these tips to keep it fresh:
- Use glass containers: Glass is the best option because it doesn’t leach chemicals. If you must use plastic, ensure it is high-grade and BPA-free.
- Seal it tight: Keep lids screwed on tight to prevent airborne contaminants and CO2 absorption.
- Keep it cool: Store your bottles in a cool, dark place away from direct sunlight. The refrigerator is great, but a pantry works too.
- Avoid chemical exposure: High-density polyethylene plastic is good for long-term storage, but keep the container away from gasoline, paint thinners, or cleaning chemicals. Plastic can be porous enough for fumes to permeate over time.
Method 1: The Pot and Bowl Technique
This is the easiest way to distill water on your stove with equipment you already own. You are essentially creating a mini rain cycle inside a pot.
What you need:
- Large stockpot (3 to 5 gallons) with a lid
- Glass or metal bowl (smaller than the pot)
- A round baking rack (or something to keep the bowl off the bottom)
- Ice cubes
Step 1: Set the Stage
Fill your large pot about halfway with tap water. Place the baking rack at the bottom of the pot. Set your glass or metal bowl on top of the rack. The bowl must float above the water line, not sit in the water.
Step 2: Heat It Up
Turn the stove to medium-high. You want the water in the pot to boil. This kills biological contaminants and turns the water into steam.
Step 3: Invert the Lid
Once boiling, lower the heat to a simmer. Take the pot’s lid, flip it upside down, and place it back on the pot. The handle should be pointing down toward the empty bowl inside.
Step 4: Add Ice
Fill the inverted lid with ice cubes. This creates a temperature difference. The hot steam hits the cold lid, condenses back into water droplets, and runs down the handle to drip into your collection bowl.
Step 5: Collect and Store
Let this process run for about 45 minutes, replacing the ice as it melts. Be careful not to let the pot boil dry. When finished, carefully remove the bowl (it will be hot) and let the water cool before bottling.
Method 2: The Two-Bottle Method
This method requires a bit more setup but is effective. You are connecting two bottles to transfer steam from one to the other.
What you need:
- Two glass bottles (one with a curved neck works best)
- Strong duct tape
- A large pot
- An ice pack or bag of ice
Step 1: Connect the Bottles
Fill one bottle about 80% full with tap water. Leave the other bottle empty. Tape the mouths of the two bottles together securely. The seal must be airtight to prevent steam from escaping.
Step 2: Position the Pot
Fill the large pot with enough water to cover the bottom bottle. Place the full bottle inside the pot. Angle the bottle about 30 degrees so the empty bottle rests on the rim of the pot.
Step 3: Create the Temperature Barrier
Place the ice pack on top of the upper (empty) bottle. This creates the cold surface needed for condensation.
Step 4: Distill
Boil the water in the pot. As the water inside the bottom bottle heats up, it evaporates, rises into the top bottle, hits the cold surface from the ice pack, and condenses into clean water. Once you have enough, let the bottles cool completely before separating them.
Method 3: Distilling Rainwater
Rainwater is nature’s distilled water (3), but it rarely stays pure. As it falls, it picks up dust, pollen, and pollution from the air. If it lands on a roof or dirty tarp, it gets even dirtier.
To make rainwater safe and “distilled-quality” for drinking, you need to collect it cleanly and then purify it.
Step 1: Clean Collection
Place a large clean container in an open area, away from trees or overhanging roofs which can drop bird waste or debris into your water. Cover the top with a fine wire mesh or cheesecloth to keep bugs and leaves out.
Step 2: Sedimentation
Let the collected water sit undisturbed for 48 hours. This allows heavy minerals and dirt to sink to the bottom. Carefully pour off the clear water from the top into a new container, leaving the sediment behind.
Step 3: Purification
The water is now cleaner, but it might still contain bacteria. You have three options to make it potable:
- Boiling: This is the simplest DIY method. Bring the water to a rolling boil for one minute, or three minutes if you are above 6,500 feet, to kill viruses, bacteria, and parasites (4). Boiling disinfects, but it does not remove chemical pollution or heavy metals, so if the runoff washed over a road or an old roof, distill it with Method 1 instead of just boiling it.
- Filtration: Use a high-quality filter with a pore size smaller than 1 micron. This removes most pathogens.
- Chemical Treatment: Iodine or chlorine tablets can disinfect the water, though they leave a taste. This is best for emergency survival situations.
