What is Distilled Water

Distilled water is just one form of purified water. Distilled water is water which has been boiled to create water vapour which is then condensed back into liquid in another container. Impurities, such as minerals, which do not boil at or below the boiling point of water are left behind thus creating purified, distilled water.

How to Distill Water

If you want to know how to make distilled water at home there are several simple techniques that you can try. The basic process is to boil tap water allowing the vapour to condense on a cooled surface and then collect the cooled, distilled water droplets. Here’s how:

  • What you will need: A large (18L or 5 gallon) stainless steel cooking pot with a lid A baking rack or trivet A glass bowl that will easily fit inside the stainless steel cooking pot Water Ice
  • Using the 18L or 5 gallon stainless steel cooking pot, fill it to about half way with tap water.
  • Place the baking rack or trivet in the bottom of the pot - this will keep a glass bowl from touching the pot bottom.
  • Place the glass bowl in the pot, either floating on the water or sitting on the baking rack which you have placed in the bottom.
  • Heat the water in the pot until it is releasing vapour and watch water droplets form in the glass bowl. Keep the heat low enough for the water in the glass bowl not to boil otherwise you will not collect any distilled water.
  • Take the lid of the stainless steel cooking pot and flip it upside down to form a bowl which you then fill with ice to create a hot to cold barrier on which the water vapour will condense.
  • Continue to steadily heat and boil the water in the pot. The water vapour rises, hitting the cold pot lid where it condenses and drips into your glass bowl.
  • Continue until you have as much distilled water as you need.

This simple technique accurately describes the process of thermal distillation. Unpurified water is heated and the arising vapour is then condensed and collected as distilled water.

The following image shows how you can make distilled water in the lab. 


  1. Unpure water is heated in the distilling flask with a bunsen burner.
  2. The arising water vapour is cooled in the condenser which is fed with cool water in the outer tube, causing the water vapour to condense in the inner tube.
  3. This distilled, purified water is collected in the receiving flask.

Purifying water through thermal distillation has been used since ancient times. It is a highly effective water treatment technique that reduces the widest range of drinking water contaminants. Desalination of seawater, making it drinkable, is one of the most common applications of water distillation. This technique is used in many arid regions of the world to create usable drinking water and water for irrigation. Until the development of small efficient reverse osmosis plants it was also used on board some ships, distilling seawater to create plenty of usable, drinkable water for passengers and crew.

Veolia Water Technologies provides industrial water distillation technologies that produce highly purified water. For example, the Polaris family of high-capacity distillation systems make highly purified, distilled water and water for injection. Water for injection is of particularly high purity with no significant contamination - demonstrating the effectiveness of the water distillation process.

How is Distilled Water Used?

Distilled water has a wide range of uses. Here are the most common applications.

Drinking Water: People often ask whether it is safe to drink distilled water and can distilled water kill you? As previously noted, the distillation process is used in the desalination of seawater to make it drinkable. It is perfectly safe to drink distilled water as part of a healthy, balanced diet. Distilled water is considered to be the purest type of water which will prevent water borne diseases and its also effective in removing toxins from your body.

Medical Applications: Surgical procedures and medical equipment cleansing uses distilled water as it free from minerals which can leave unwanted deposits. Also, high-purity distilled water is required as water for injection.

Laboratory Applications: Laboratory processes and experiments require highly pure water that will not cause contamination. High purity distilled water is typically used.

Engines and Automobiles: Distilled water is typically used in engine cooling systems as it does not contain minerals which can cause corrosion. It is also used to top up the sulphuric acid electrolyte in lead-acid batteries.

Industrial Applications: Distilled water is valuable across a wide range of industries. The food and beverage industries, for example, require consistent supplies of high purity water. Also, the pharmaceutical and chemical processing industries are major users of distilled water.

Where to Get Distilled Water

Distilled water can sometimes be found in the car accessories section in major supermarkets. Another source is via well-known online general suppliers. But you are likely to find that these sources are quite expensive if you need a significant amount of distilled water.

A more practical solution, in the long term, would be to use your own water distillation system. Water distillers for home use are readily available at very reasonable prices and will produce good quality, distilled water that is free from the impurities typically found in tap water.

For medical, laboratory and many industrial applications, high-volume systems are typically required and in many cases double distillation is needed in order to achieve extremely high levels of water purity. Veolia Water Technologies has a wealth of experience in water treatment system design and the implementation of distilled water treatment requirements.

The following image shows a Polaris distillation system, as supplied by Veolia Water Technologies. 


People often ask: Can I use boiled water instead of distilled water?

While boiling water will kill water-borne organisms, making water more safe to drink, it will not remove endotoxins or minerals . When water is distilled both the water-borne organisms, endotoxins and the minerals are no longer present in the distillate. So boiled water would not be good to use in any application where mineral deposits or endotoxins will cause problems.

Another question that is often asked with regard to distilled water is: Is distilled water the same as deionised water?

While distilled water and deionised water are both forms of high purity water they are made using different processes.

Deionised water is typically created by firstly filtering the water to remove organic impurities. Then the water is passed through the deionisation system which attract positive and negative ions, ultimately replacing these with water.

As described, distilled water is made by heating to create vapour which is then condensed. Distilled water is generally considered to be more pure as it should not contain any bacteria or other pathogens which could, in theory, remain in deionised water.

Deionised water tends to be cheaper and easier to make so it is often used in cooling applications, industrial processes, laboratories and pharmaceutical applications.

Yet another question that is often asked is: Is rainwater the same as distilled water?

This is a very good question as rainwater is derived from clouds which are formed from evaporated water rising into the atmosphere and condensing. But it must be remembered that the water vapour is not created from boiling the source water so rainwater cannot be considered the same as distilled water. Rainwater picks up whatever is in the earth’s atmosphere including dust particles and importantly, gases. This is what creates acid rain.

Ranj Rihal

About the Author

Ranj Rihal

Ranj Rihal has been with Veolia Water Technologies for over 25 years. He is currently responsible for market activities for pharmaceutical and cosmetics industry providing support to the many VWT Business Units around the world, with respect to technical, process, commercial, market and product knowledge. Ranj has held positions as Senior Project Engineer and Senior Proposals Engineer for VWT supplying water treatment systems to the Pharmaceutical and Cosmetics Industry worldwide.