MadSci Network: Environment & Ecology

Re: why does water change colors and have odors and odd tastes?

Date: Wed Jan 14 14:26:09 2004
Posted By: Tony Gaglierd, Assistant Professor , Natural Science and Engineering Technology
Area of science: Environment & Ecology
ID: 1071812264.En

Why dose water change colors and have odors and odd taste?

Generally color in water may be of natural mineral or vegetable origin, 
caused by metallic substances such as iron and manganese compounds, humas 
materials, peat, tannins and lignin’s, algae, weeds and protozoa. 

Waters may also be colored by inorganic or organic soluble wastes from 

True color in natural water is caused by dyes derived from decomposing 
leaves or other vegetable matter. A substance from rotting oak leaves and 
iron in water will combine to cause an inky color or tint. Generally the 
color will be brown or dark read, caused by tannic acid or humic acid. 
When the substance from decaying oak leaves react with chlorine used for 
disinfect ion a very strong phenolic – iodoform odor is imparted to the 

Tastes and Odors in water can be caused by minerals in the water. Examples 
are a salty taste apparent when chloride levels are present at 500ppm or 
grater. The “rotten egg” odor caused by Hydrogen Sulfide in some well 
waters. However, most objectionable tastes and odors in potable water are 
caused by biological activity. Many species of algae, diatoms and 
actinomycetes produce essential oils. These essential oils when released 
into the water, particularly when large populations of organisms die, 
produce objectionable tastes and odors. Usually these effects are seasonal.

As to why the drinking water in the fountains at you school change colors 
and has an odd taste, I can only give some broad explanations since I 
would need to know more about your towns, or school’s source of water is 
it public or do you have a well? What is the source of the public water, 
surface water or ground water? What treatment is provided? Where do you 
live? What is going on in the distribution system, leaks, repairs 
maintenance, line flushing? Are you on a dead end line?

Assuming, because of the requirements of the Safe Drinking Water Act that 
the water leaving the supplier meets standards, then the problem may be in 
the distribution system. Rust and sediment in the lines could be being 
stirred up due to high velocities or disturbances in the water lines. Your 
school could have old galvanized steel piping, this could be the cause of 
the problem. Or there could be a problem with the water supply that is not 
adequately addressed during treatment.

Be a scientific detective. Try to get the answers to the questions I posed 
above. Talk to the operators at the water plant I’m sure they can better 
answer your specific questions about your towns and schools water supply.

Let me know what you find out.

e-mail me at

Thanks for writing the Mad Scientist network and good luck on you project.

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