Walter Louis Fluid Technologies
Potable Water Monthly Newsletter, September, 2012
Taste and Odor
Potable water, by definition, should be free of taste and odor. In general, a public water supply should meet the following criteria:
1. It must contain no disease-producing organisms
2. It must be colorless and odorless
3. It must be good tasting, free from odors, and preferably cool.
4. It must be non-corrosive
5. It must be free from objectionable gases such as hydrogen sulfide, and objectionable staining materials such as iron and manganese
6. It must be plentiful and at low cost
While the presence of disease-causing organisms or toxic chemicals can render a water supply unsafe to drink, other factors such as odor, color, and mineral content can cause its aesthetic properties to render it non potable. Some of the common causes of taste and odor include:
1. decaying organic matter
2. living organisms
3. iron, manganese, and the metallic products of corrosion
4. industrial waste pollution from substances such as phenol
5. high mineral concentrations
6. chlorination
7. dissolved gases
Taste and odor are very closely related because of how closely our senses of smell and taste work together. Sulfur water, as some people call it, is really water with hydrogen sulfide gas present. Although it seems to have an awful taste, the real problem with it is the hydrogen sulfide gas emitting from the water and this is what we are sensing when we try to drink it. Oxidation of sulfide to sulfate is one method for treating a hydrogen sulfide bearing water. Another is just to aerate the water and allow the hydrogen sulfide to evaporate.
The causes of taste and odor are so numerous that it is impossible to suggest a treatment to remove all of them. There are, however, many common products which will destroy the most common contaminants. Tastes are generally classified into four groups-sour, salt, sweet, and bitter. Odors, on the other hand, have many classifications-some 20 to be exact. Some of the more common of these are fishy, earthy, grassy, and musty. Some of the common causes of these include humic acid, fulvic acid, and tannic acid, all resulting from decaying organic materials. These acids are huge organic molecules.
Many common oxidizing agents are very effective on these big molecules. They destroy the odors by breaking up the large molecules into smaller ones. Potassium permanganate, while useful for removing manganese, is also very effective in destroying odor causing substances. It is especially effective on musty, fishy, grassy, and moldy odors. Chlorine is a very effective oxidizer as well except it has the added effect of forming chlorinated hydrocarbons such as HAA’s and THM’s and we all know those should be kept at a minumum. Other less common oxidizers are ozone and hydrogen peroxide.
Activated carbon is very effective for removing many of these large compounds and their smaller by products by a process called adsorption where the molecules become trapped in the microscopic pores in the carbon particles.
There are many types of activated carbon so the correct one needs to be selected.
This has been a brief discussion of the most common causes of and the most common treatments for taste and odor. As stated, there are numerous other causes of taste and odor which can render a water supply non-potable.
In some cases it is actually more economical or practical to find another water supply than to treat one which has unusual contamination.
We at Walter Louis are ready to assist anyone with issues pertaining to taste and odor. Please give us a call. Our office phone is 800-747-2019. Or we can be reached at sales@walterlouis.com. Thank you.