Many people do not know what is pure, clean or potable water. This stems from not having a simple metal model of water in mind to answer the questions. Thus, the marketers rely on divas of yester years or sportsmen who have retired to be influencers to but for their water purifiers.
I get three questions in mind when I see water viz.
Water can be described through many properties. These parameters are divided into Physical, Chemical and Biological properties. Most of them fall in either of these categories
A combination of theses properties gives unique quality to water. Let’s look at typical lake water supplied by Brihan-Mumbai Municipal Corporation (BMC). A typical observation reveals that it is clear, colorless, odor free, taste quite good, does not typically have dirt (may be in monsoon time one may find some dirt) and is at room temperature if it is collected from the tap. We do not know the chemical or biological properties until we measure them because they are not observable by our senses. These good properties intuitively tell us that water may be drinkable.
Let’s look at the gutter water. What are the typical observations? It is turbid or looks unclean, has suspended matter, has a grayish color, smells foul, we can’t taste it because of foul odor (you should NOT taste it). Again, we cannot measure chemical and biological properties unless we have access to a laboratory. These are the properties which tell us if it is usable or not usable.
At a slightly deeper level, I measure some physical & chemical properties of water such as color, odor, suspended matter, pH, Total Dissolved Solids, Total Hardness and Total Alkalinity. These measured properties tell a story. It tells me the source of water, the minerals it has picked up, is the water is alkaline or acidic, is it heavy to digest and will it form scales (whitish salt deposits)if used. With experience this much analysis allows me to develop a basic scheme for water treatment too. Please note, I do not do biological tests at this stage, especially if I know the region well. I assume that biological contaminants will be present and suggest an appropriate scheme to take care of biological contaminants. If the source or region is unknown, I do a total bacterial count, coliform bacteria and e.coli count. This gives me an idea if the water is potable or not potable.
A third level deeper analysis of physical, chemical and biological properties is necessary to develop a detailed treatment process, to find a new source of potable water, diagnosis of water problems or develop a water quality protocol for specific use such as mineral water or intravenous injection water. The property analysis protocol needs to be developed for a specific use. For example, for a water treatment company I developed a specific protocol which tested some common physical, chemical and biological properties but also tested for a type of extremely resilient bacteria called pseudomonas which contaminated the water equipment which was used for preparation of intravenous injection water.
In summary, a mental model for a particular type of water is a combination of physical, chemical and biological parameters. These properties define the type of water. This mental model provides a simple way to think about water.
If you have any questions about water, feel free to reach out. I would love to hear from you.