What Is Distilled Water?
Distilled water is water that has been boiled into steam and condensed back to liquid, leaving minerals and impurities behind.
How distilled water is made
Distillation uses the different boiling points of water and what is dissolved in it. Water boils at 100 °C (212 °F) at sea level; salts, minerals and metals do not boil off at that temperature. The steam rises, leaving them behind, then cools in a condenser and drips into a clean container as distilled water.
- Heat tap water until it boils.
- The steam rises away from the dissolved solids.
- Cool the steam so it condenses.
- Collect the liquid. That is distilled water.
Distilled vs other types of water
| Type | How it is treated | Minerals left |
|---|---|---|
| Tap water | Disinfected | Yes |
| Spring or mineral water | Natural source | Yes |
| Purified water | Filtering, reverse osmosis or similar | Few |
| Distilled water | Boiled and condensed | Almost none |
| Deionised water | Ion exchange | No ions (may keep some non-ionic contaminants) |
What distilled water is used for
- Labs: making solutions and rinsing glassware, because minerals would react or leave deposits.
- Appliances: steam irons, humidifiers, CPAP machines and car batteries, to avoid limescale.
- Medical and cosmetic: preparing sterile products (with further sterilising).
- Aquariums and coolant systems: where mineral build-up is a problem.
Try it in our virtual Chemistry Lab, where water is the base for most solutions, and see why dissolved ions matter in the pH Calculator.
Frequently asked questions
What is distilled water?
Distilled water is water that has been boiled into steam and then condensed back into liquid. Minerals, salts and most other impurities stay behind, so the result is very pure H₂O.
Is distilled water safe to drink?
Yes, it is safe to drink, but it tastes flat and has no minerals. You get most of your minerals from food, so occasional drinking is fine; it is mainly used for irons, car batteries, lab work and medical equipment such as CPAP machines.
What is the difference between distilled and purified water?
Purified water is any water treated to remove contaminants (by filtering, reverse osmosis, deionisation or distillation). Distilled water is purified specifically by boiling and condensing it.
What is the pH of distilled water?
Ideally 7, but in open air it absorbs carbon dioxide and becomes slightly acidic, usually around pH 5.5 to 6.
Can you make distilled water at home?
Yes. Boil water in a covered pot and collect the condensed steam from the lid in a clean bowl. Let it cool and store it in a clean, sealed container.
