Pure water and ultrapure water - where is the difference?

Sometimes you hear about pure water, sometimes ultrapure water. Whether there is a difference between the two types of water and what exactly it is for is explained in detail in this article.

Definition of pure water

Pure water is any type of purified water, regardless of its quality criteria. It is not a technically defined concept but a concept of common usage.

In water treatment, for example, one speaks of "raw water" and "pure water" before and after the water treatment process. Pure water is therefore only previously purified water

ultrapure water

Ultrapure water is water that is purified with special methods and has very little or no soiling. Already distilled water is ultrapure water.

In addition, there are technically still other stages of water purification. For example, multiple distillation is also possible. Double-distilled water, the so-called bidestillatus, is used in drug manufacturing.

The pharmaceutical industry in particular often requires very highly purified water. Triple distillates are also common. However, the European Pharmacopoeia only defines the quality requirements for the so-called "Aqua Valde Purificata", ie very intensively purified water.

Quality criteria for high purity water

An important measure of the purity of water is the electrical conductivity. The lower it is, the cleaner the water is. This is because with the removal of the impurities no mobile charge carriers are more available and the electrical line only takes place via the so-called autoprotolysis.

For Aqua Valde Purificata a maximum conductivity of 1.1 μS / cm at a temperature of 20° C is prescribed.

In addition, the total carbon content of the water must not exceed 0.5 mg / l and the nitrate content must not exceed 0.2 mg / l. Bacterial toxins must not exceed 25 ng / l (so-called bacterial endotoxins). Notwithstanding this basic requirement, there are still some other technical limits that must be complied with.

Tips & Tricks

Drinking high purity water or distilled water can be very harmful to your health. It is by no means a health product, even if it is very pure. It can even be poisonous.

Video Board: Ultra-Pure Water | National Geographic