What is distilled water used for?

Written by William Fryer - MA Oxon

Distilled water is water that has been boiled, turned into steam and then re-condensed as absolutely pure, (distilled) water. As well as a drinking water, distilled water has multiple uses both around the home and industrially.

Steam Irons

It's best to use distilled water in your iron at home. Your iron generates steam, the water in a steam iron often leaves behind a residue (scale) which can block up your iron. However, if you use distilled water in your iron, you do not get this residue build-up and your iron lasts longer.


Fish actually love distilled water. Think about it, rain is distilled water, so it is the perfect medium for fish. You can also create the exact aquatic habitat your need without having to worry about toxins like chlorine harming your fish.

Watering the plants

Again, distilled water is THE BEST water to use for your plants because it is the closest thing to rain water (rain is distilled water).

Car cooling systems 

Abit like steam irons, if you use tap water in your car’s cooling system it can lead to corrosion and blockage.

Lead acid batteries

Lead acid batteries like those in your car use distilled water to dilute acid to allow the electrical current to flow through the sulphuric acid. If you use tap water, it potentially upsets the electrolyte balance and does not conduct electricity so well, so you destroy your battery. Always use distilled water to top up a lead acid battery.


Labs use distilled water. They use distilled water because scientists prefer to use pure chemicals. Contaminants cause errors.


Lots of medical treatments use distilled water. It is used to dissolve drugs which might need to be given intravenously. It is used in autoclaves which are a type of machine used to sterilise medical instruments. And it gets used in CPAP machines which are used to help people with certain breathing problems to breathe.

Distilled water for making Ice

Distilled water produces crystal clear ice

Distilled water for cleaning

Leave glass cleaner on the shelf in the supermarket. Instead, use half distilled water and half vinegar to clean your glass.

Distilled Water for CPAP Machines

To use CPAP machines you need virus, bacteria, and contaminant free water - distilled water.

Distilled Water for Dogs

Some vets recommended giving your dogs distilled. It’s meant to help with allergies, sensitive stomachs and prevent them catching any waterborne diseases.