Can you plz tell me which factors determine the quality of potable water?

Question

dont tell what is potable water

just tell how can you determine its quality.

Answer 1

u dont get diarrhoea after drinking it...

Answer 2

It is not poisonous and it tastes OK

Answer 3

This is a rather vague question, but I'll take a stab at it.

I'm going to go with three things that determine the quality of water - physical characteristics, chemical characterists, and biological characteristics. Each one of these may render water non-potable.

The simple answer is physical characteristics: taste, odor, and color. If it tastes or smells bad you won't want to drink it. And if it is colored - such as yellow - you're not going to want to drink it either. For this reason the EPA lists these variables as "secondary water standards". Water that tasts, smells, or looks funny is going to be non-potable and of poor quality.

Now the more complicated answer, and one would guess that this is the answer that a textbook would want, is based on water chemistry. In general water quality is primarily concerned with the dissolved substances within it. The most common substance dissolved within water that makes it non-potable is salt. In Florida, at least, we define water of poor quality as anything that fails under the secondary standards, which includes those factors of taste, smell and color listed above, but also includes a chlorides (sort of like salt) concentration of 1500 parts per million or so.

Those are the secondary water standards. Water also has to be free of dissolved contaminants as well. In many cases, one cannot taste the contaminants in water yet it is still hazardous to drink and thus non-potable. I don't know how long the list of known groundwater contaminants is, but I think it is around 500 or so. Methyl tert-butyl ether (MTBE) is a good example of a dissolved chemical that you cannot taste at hazardous levels.  If enough MTBE is dissolved in the water, it is of poor quality and non-potable. Thus chemicals dissolved within water determine water quality as well.

But that is not all - on top of chemistry there are biological issues. You cannot taste bacteria in the water, yet certain bacteria may be hazardous to your health as well. Thus, a water sample must also be tested for the presence of biological agents. Water loaded with hazardous bacteria agents would be poor quality as well. Generally you find this in lakes, resevoires and recycled water; I'm not all that familiar with biological problems with water.

That gives you three general factors and several specific factors that determine quality of potable water - physical characterists, chemical characteristics, and biological characteristics.

As for how you actually determine the quality of the water, you take one or more samples and send them to a laboratory. Laboratory analyses gets into chemistry, biology, and a boatload of statistics, and would require a rather lengthy seperate answer.