Some means of reducing water hardness as we've described in preceding blogs is an almost universal first step in making water pure enough for most cleaning applications. But water softening only addresses the removal of only a few of many contaminants that are commonly present in our water supplies. The remaining contaminants range from ions (other than those removed in the water softening process) to things as large as beach sand. The following illustration published several years ago by Osmonics shows the absolute and relative size of many of the contaminants we commonly find in water.
The above illustration shows not only the size but also the diverse types of contaminants found in water supplies. For a full-sized PDF, click on the link below.
The Filtration Spectrum(osmonics)
As you might imagine, different applications require the removal of different impurities. An application requiring water that won't scratch or abrade critical components will, naturally, focus on removing particles from the water supply. A medical application, on the other hand, might focus on removing bacteria and pyrogens with no real concern for non biologically active agents. The range of different equipment and techniques for purifying water is as broad as the requirements for the purity of water.
Determining the purity of water required for a particular application is a critical part of the development of a cleaning process. Higher purity water almost inevitably means higher equipment and maintenance costs which must be justified. Furthermore, it is NOT just the purification of the water that is important and costly. Once water has been purified, it must be handled appropriately to prevent re-contamination. Pure water delivered through a contaminated plumbing system will no longer be pure. Maintaining water purity dictates certain plumbing features that, otherwise, would be of no concern. Finally, overly pure water can, in some cases, be just as detrimental to a process as water that is not pure enough. High quality de-ionized water, for example, is so "hungry" for ions that it is corrosive to many metals and may cause discoloration.
So there is a lot for us to know about water and water quality. We have discussed simple particle filtration at some length in preceding blogs (search "filtration"). In the next few blogs we'll "ramp it up" a little and look at removing things that particle filters alone will not remove.
- FJF -