What Is Distilled Water and How Is It Made?

Distilled water is water that has been boiled into steam and then condensed back into liquid. The minerals, salts and most impurities found in tap water are left behind, giving you very pure H₂O.

How distillation works

1. Water is heated until it turns to steam.
2. Dissolved minerals such as calcium and magnesium do not evaporate, so they stay behind.
3. The steam is cooled and condensed into a clean container.

The result is water with an extremely low mineral content.

Why not just use tap water?

Much of the UK has hard water. When hard water heats up or evaporates, it leaves limescale. That scale can block steam irons, damage humidifiers, shorten the life of batteries and spoil DIY recipes. Distilled water does not leave these deposits.

Popular uses

• Steam irons and garment steamers: prevents scale build-up and white flakes on clothes.
• Car and leisure batteries: topping up lead-acid cells.
• Cooling systems: mixing with coolant concentrate.
• Humidifiers and diffusers: no white dust or scale.
• DIY cosmetics and soap making: consistent, predictable results.
• Diluting IPA, hydrogen peroxide and castile soap.
• Aquariums and plants: as a base for remineralising.
• Laboratory and workshop use.

Is distilled water the same as deionised?

Not quite. Deionised water has had charged ions removed by resin, while distillation removes minerals by boiling. Both are low in minerals, but distillation also leaves behind many non-ionic impurities. We cover this in a separate guide.

Storing distilled water

Keep the cap on and store away from direct sunlight. Once opened, use clean equipment so you do not contaminate the rest of the container.

Shop: Distilled Water, Ultra Pure from 5L up to 4x5L, ideal for households that get through a lot.