Information Only: Total Trihalomethane Levels

South Sioux city purchases water from Sioux City from time to time and Sioux City’s four-quarter-average of the disinfection byproduct, Total Trihalomethane (TTHM), was found to be 0.083 mg/L at a particular location, which slightly exceeds the MCL (maximum contaminate level ) of 0.080 mg/L.

To give a little background information, disinfection byproducts (DBPs) are not like other water contaminants which stay at a constant level.  DBPs are formed when natural organic matter reacts with chlorine or other disinfectants.  DBP levels can fluctuate and are determined by such factors as:  organic matter levels, disinfectant type, disinfectant concentration, water temperature, water pH, and reaction time.  In general, and depending upon the disinfectant type, larger distribution systems tend to have higher concentration of DBPs because the disinfectant has been in contact with the natural organic matter in the water for a longer period of time.

South Sioux City’s levels are 0.025 mg/L, and  0.026 mg/L  and these levels are well below the MCL  (maximum contaminate level )

EPA agreed that South Sioux City is not required to notify its customers of Sioux City’s high TTHM levels since our own levels are well within the limits, and  it doesn’t appear that disinfection byproducts, including TTHM, are an issue in South Sioux City. However we do  pass this information on to our customers


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City Hall 1615 1st Ave
South Sioux City, NE 68776
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