Water Purity and Its Meaning
When we say water purity, what do you think?
‘Ehh… how pure the water is?’
However, if to think deeper, it is actually hard to define purity.
Water purity is a complex term to understand clearly. Are we talking about water contamination? Are we
about pollution? In the United States, the EPA defines "pure" water as water free from all types of bacte
viruses. But there is more to purity than just that.
Water is a compound made up of hydrogen and oxygen, so pure water would be water that contains not
hydrogen and oxygen. However, pure water of this sort does not normally exist except in the controlled
environment of a laboratory. Even in a laboratory pure water is hard to come by. For example, bacterial
contamination of purified water can cause major problems in the laboratory. Even if organic and inorgan
impurities are removed down to the limits of detection, bacterial growth can still occur, even though ver
water provides an extremely harsh environment with apparently negligible nutrient content. To avoid m
contamination of the water, laboratory water purifiers are constructed using plastics. The bacteria can u
materials that are in contact with the pure water as a carbon food source to sustain them, and then whe
they release further contaminants into the water. If this bacterial growth is not minimized, it can cause
difficulties in the day-to-day operation of the laboratory.
From a drinking water standpoint, most references to "pure water" are in relation to bacteria content an
chemical contaminant concentrations. The bacteria in pure water themselves are not the only problem;
produce endotoxins and nucleases. Endotoxins are fragments of Gram-negative cell membrane that are
during bacterial cell metabolism, and are also produced at the death of Gram-negative cells.
Endotoxins — the most common pyrogens — are powerful immune stimulants, raising temperature if th
injected into the bloodstream. This can even lead to Gramnegative sepsis and death. Ultraviolet irradiati
very effective at destroying micro-organisms. Although it is not a barrier process, relatively low energy d
ultraviolet light greatly reduce overall bacterial levels, minimizing the challenge on downstream purificat
processes.
There’s no such thing as pure water. The very concept of ‘pure’ water is misleading. Pure water does no
nature. Water is the universal solvent. Even as it falls to earth as rain it picks up particles and minerals
And as soon as it hits the ground it captures minerals from the soil and rock upon which it lands. It mak
into streams and rivers, carrying soil from the mountains to the sea. Water picks up contaminants such
mercury while it’s falling as rain.
Consumers can achieve healthy water by identifying the unhealthy contaminants in their water and then
action to remove them. In general, the public discussion about water can and will switch from the notion
to ‘healthy’. Healthy water is attainable, whereas pure water is not. And just what is healthy water? Hea
can have an optimum pH of 7.2 to 7.6. Harmful contaminants such as chlorine, chloramines, disinfection
products such as the trihalomethanes, and any harmful chemical or metals whether man made or natur
occurring have been identified and removed with the appropriate treatment.
