Series No. 874
Contaminants in drinking water always are cause for concern. However, it is important to distinguish between the acute and chronic effects of harmful substances.
In Idaho and the rest of the nation the most commonly detected drinking water problem is bacterial contamination caused by improper well construction and maintenance. Bacterial contamination is a common cause of acute toxicity, producing symptoms as mild as upset stomach and diseases as serious as dysentery, typhoid fever and hepatitis. Household cleaners and garden chemicals are other examples of contaminants that can produce acute effects.
Over time, some drinking water contaminants can damage the liver, kidneys, heart and other body organs. Health officials are almost always concerned about chronic effects of drinking-water contaminants such as low-level nitrates, radon and volatile organic chemicals. Such effects may include cancer or damage to the central nervous system.
Drinking Water Standards
The Environmental Protection Agency (EPA) standards for drinking water fall into two categories -- primary standards and secondary standards.
Contaminants or potential contaminants covered by Idaho regulations include hazardous, deleterious and radioactive materials; floating, suspended or submerged matter; excess nutrients; oxygen-demanding materials and sediment. Standards for Idaho water quality are established and enforced by the Division of Environmental Quality, Idaho Department of Health and Welfare. While existing standards help ensure safe water, standards do not exist for many additional contaminants.
|Substance||Maximum allowable concentration|
|(mg/l or ppm)|
|up to 12.0 C (54 F)||2.400|
|12 C (55 F) -- 15 C (58 F)||2.200|
|15 C (59 F) -- 18 C (64 F)||2.000|
|18 C (65 F) -- 21 C (71 F)||1.800|
|22 C (72 F) -- 26 C (79 F)||1.600|
|26 C (80 F) -- 32 C (90 F)||1.400|
|Nitrate (as N)||10.000|
|Sodium||No maximum established;|
20 suggested as optimum
|2, 4, 5-TP Silvex||0.010|
|Coliform bacteria||2 per hundred
for any individual sample
(NTU) for any individual sample
|* As determined by the average annual maximum daily air temperature for the area where the water is to be used.|
The Authors -- Roy Taylor is Extension agricultural engineer, Ernestine Porter is Extension textiles and clothing specialist and Robert L. Mahler is soil scientist and Extension water quality coordinator, all in the University of Idaho College of Agriculture, Moscow.
|This publication is one of a series on water quality issues produced by the University of Idaho Cooperative Extension System for the people of Idaho. The material is based upon work supported by the U.S. Department of Agriculture, Extension Service, under special project number 90-EWQUI-1-9216.|
Issued in furtherance of cooperative extension work in
agriculture and home economics, Acts of May 8 and June 30, 1914, in
cooperation with the U.S. Department of Agriculture, LeRoy D. Luft,
Director of Cooperative Extension System, University of Idaho, Moscow,
Idaho 83844. The University of Idaho provides equal opportunity in
education and employment on the basis of race, color, religion,
national origin, gender, age, disability, or status as a Vietnam-era
veteran, as required by state and federal laws.
|8M 9-90, 400 2-93
Printed with special grant funds from USDA
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All contents copyright © 1997-2002. College of Agricultural and Life Sciences, University of Idaho. All rights reserved. Revised: January 3, 2002