A Complete Guide to Distilled Water

There are many types of purified water, and distilled water is one of the most pure. In our Complete Guide to Distilled Water, we’ll explore what it is, how it’s made, its uses, benefits, and specifications. You’ll also find further information and reading material in the links at the bottom of this page, and of course you can buy distilled water from ReAgent, one of the UK’s leading distilled water suppliers.

What Is Distilled Water?

Distilled water is water that has been heated into a vapour and then condensed back into liquid form. This process (called distillation) removes almost all the water’s impurities, including ions, minerals, and organic impurities. This makes distilled water one of the purest forms of purified water.

Distillation produces purer water than other methods of purification such as deionisation and demineralisation, which use ion exchange resins to remove ions to form pure H2O. These methods, while producing pure water, cannot remove organic impurities as distillation can.

Organic Impurities Removed By Distillation

The organic impurities which are removed in the distillation process include:

  • Arsenic
  • Asbestos
  • Bacteria
  • Fluoride
  • Herbicides
  • Lead
  • Mercury
  • Nitrate
  • Trichloroethylene
  • Pesticides
  • Viruses
  • Water-borne contaminants


Distilled, Demineralised and Deionised Water

Distilled, deionised and demineralised water are all types of purified water that have been processed and separated from their impurities. They each use a different production process:

  • Deionisation: ion exchange resins remove ionic impurities such as calcium, magnesium, and nitrate from water
  • Demineralisation: similar to deionisation, demineralisation uses ion exchange resins to remove mineral salts
  • Distillation: water is heated into a vapour and condensed back into a liquid

Distilled water is typically more expensive than deionised and demineralised water as the process of distillation takes longer. Deionisation and demineralisation are much quicker and more efficient processes. Because of that, deionised or demineralised water are commonly used when it’s not essential to use distilled water.

Is Distilled Water the Same As Boiled Water?

The short answer is no. Boiled water and distilled water are two different products that have treated in two different ways.

The difference is that boiled water is not purified water, so it can’t be used when high purity water is required. As we’ve already seen, distilled water is one of the purest forms of water available. It has been physically separated from its impurities. Boiled water is not processed in the same way, so boiled water is not the same as distilled water because it isn’t pure.

How Is Distilled Water Made?

Distillation is an ancient form of water purification. We know this because Aristotle (b. 384 BCE) references the process in his work. It involves physically separating water from its impurities – distilled water isn’t produced through a chemical reaction, rather the impurities are are separated from water using a process of evaporation and condensation.

Most organic impurities found in water have a higher boiling point than the water itself. This means that they will not evaporate along with the raw water once that reaches boiling point, but will stay behind.

Distillation may seem like a simple process, but on an industrial scale the reality is quite precise and complex.

Making Distilled Water on an Industrial Scale

A Complete Guide to Distilled Water - how to make distilled water

A factory producing distilled water uses multiple distillers which include a couple or more boiling chambers. In essence, the distillation process on an industrial scale is:

  1. Raw water goes into the first boiling chamber. This chamber puts the most pressure on the water at the beginning of the distillation process. The pressure on the water in each consecutive boiling chamber decreases.
  2. The steam produced in the first chamber is of a temperature which far exceeds the temperature of the next chamber, and so on through the chambers.
  3. Steam passes through each chamber at decreasing pressures.
  4. Steam passing through pipes from one chamber to the next vapourises the water in the pipes, and this makes the distillation process continuous.

When exceptionally high purity water is required, distilled water is reprocessed in the same way. This is called double distillation and it is used to ensure that the final product is as pure as possible.

Uses of Distilled Water

Its high purity means that distilled water isn’t corrosive, doesn’t leave a residue behind and doesn’t react with other chemicals. This means that distilled water has a wide range of industrial applications.

Pharmaceutical Manufacturing

Extremely high purity water is used in the pharmaceutical industry as contaminants in lower purity water interfere and react with other ingredients and materials. Although demineralised water is sometimes used to decrease costs, when the process or product requires high purity water, distilled is used.

Distilled water is used in pharmaceutical products such as:

  • Analytical reagents
  • Active pharmaceutical ingredients
  • Active pharmaceutical intermediates


Medical Procedures

Water used in or as part of medical procedures has to be of very high quality and meet strict standards. Distilled water is used in medical procedures to:

  • Clean instruments, as it doesn’t contain minerals which cause spotting
  • Remove any detergent that may be on medical instruments
  • Clean wounds, to reduce the chances of tissue infection and prevent the spread of bacteria
  • Irrigate wounds during surgery to prevent bacteria from getting into the body
  • Rinse your mouth during a dentist appointment to prevent infection of an open wound


Laboratory Applications

Distilled water is used in the lab in various ways, and one of the most important of those is lab testing. Lab testing requires extremely accurate procedures where only the variables being tested are changed. In order to ensure analytical integrity, that results are reliable, and the data is accurate, high purity water which doesn’t impact on testing by reacting with other chemicals, contaminating formulations or leaving trace impurities is used.

Distilled water is also used in the lab:

  • As a solvent to prepare solutions and buffers
  • To clean glass and delicate equipment
  • To ensure the high quality of the product you’re making

A Complete Guide to Distilled Water - use distilled water in laboratory applications


Distilled water is commonly used in vehicle engines and lead-acid batteries. Because it doesn’t contain minerals, using distilled water extends battery life as it doesn’t corrode metal through mineral build-up in the way that less pure water can.

The high grade purity of distilled water means it is also used in:

  • Engine cooling systems
  • Aircraft engines
  • Gas-turbine engines
  • Boiler systems in steam engines


Manufacturing Cosmetics

Water is crucial in the manufacture of cosmetic products, from make-up, soap, and creams to shampoo and conditioner. Its main use is in its capacity as a solvent, and it’s used to dissolve the ingredients used to make cosmetics.

Because distilled water is pure H2O, this is the grade of water that cosmetic companies typically use. Distilled water doesn’t contain any contaminants which could interfere with the cosmetic product formulations or act as an irritant on the skin.

Other Uses of Distilled Water

While we’ve looked at some of distilled water’s most common uses, it is also used in many other applications, such as:

  • Cleaning circuit boards in the electronics industry
  • In humidifiers to avoid mineral deposits
  • For canning fruit and vegetables – distilled water maintains the colour and taste of the food, and doesn’t turn cloudy with mineral build-up

A Complete Guide to Distilled Water - use distilled water in canning fruit and veg

Benefits of Distilled Water

The benefits of distilled water are linked directly to its uses and include:

  • High purity
  • Non-corrosive
  • Doesn’t leave a residue
  • No scale build-up
  • Excellent solvent
  • Rapid manufacturing time

Can You Drink Distilled Water?

‘Regular’ water contains impurities and while this may not sound like something you want to drink, these impurities are actually crucial minerals our bodies need, such as calcium and magnesium. Consistently drinking distilled water means you are depriving your body of essential ions and minerals it needs for key biological functions (and it doesn’t taste that nice either!).

The distilled water we manufacture at ReAgent is extremely high purity and definitely NOT suitable for consumption.

A Complete Guide to Distilled Water - can you drink distilled water

Hazards Of Distilled Water

Distilled water poses no hazards in normal industrial use, including physical, health or environmental hazards. It is not flammable, it’s stable, and no classified risks have been identified.

Distilled Water Specification


pH @ 25°C4.5 – 8
Conductivity @ 25°C0 – 5µS/cm

Distilled Water Material Safety Data Sheet (MSDS)

Distilled water is not classified, so it doesn’t require a material safety data sheet. At ReAgent, we provide a distilled water safety data sheet for relevant user advice. Under the Registration, Evaluation, Authorisation and Restriction of Chemicals manufactured in or imported into the E.U. (REACH), material safety data sheets are referred to as safety data sheets (SDS).

Where To Buy Distilled Water

Businesses Buying Distilled Water

If you are a business who would like to buy distilled water from an established, reputable chemical supplier, you can buy from us right here at ReAgent. The benefits?

  • Focus on reliability – we make sure you get what you need when you need it
  • We have thousands of happy customers from more than 40 years in the chemical industry
  • We are experts in supplying various grades and types of purified water
  • Free pre-purchase and after-sales support
  • Quality accredited, including ISO 9001 and ISO 14000

We also make to order and provide conformity and analysis certificates if needed (additional charges may apply).

However, at ReAgent we don’t supply distilled water direct to consumers.

Consumers Buying Distilled Water

You can buy distilled water from many large supermarkets, hardware stores, and online from retailers such as Amazon. The type of distilled water you buy as a consumer isn’t made to order, so the quality probably won’t be as good and you’d normally only buy it in small amounts.

If you buy distilled water online, it’s always worth checking the seller’s credentials as they probably won’t be an established chemical supplier. That means they may not have the same strict quality standards or any quality accreditations.

Buying online also means you’re adding another link in your supply chain, which can be complicated. It’s also likely that you won’t get the pre- or after-sales support you might need.

If you only need a small amount to use at home and want to reenact a chemistry lesson, you can also make your own distilled water.


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