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Distributing groundwater without a disinfectant residual
Author(s) -
Hambsch Beate
Publication year - 1999
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.1999.tb08572.x
Subject(s) - disinfectant , residual , chlorine , odor , groundwater , heterotroph , microbiology and biotechnology , chemistry , colony forming unit , environmental chemistry , zoology , food science , environmental science , pulp and paper industry , biology , bacteria , mathematics , organic chemistry , geotechnical engineering , algorithm , engineering , genetics
In Germany, high‐quality groundwater may be distributed without a disinfectant residual. Microbiological data on drinking water in a distribution system were compared before and after the treatment plant discontinued use of a chlorine residual. Bacteriological assessments of chlorinated groundwater consistently showed heterotrophic plate counts (HPCs) < 5 colony forming units (cfu)/mL, a count indicating that bacterial regrowth was very unlikely. Because chlorination that produced about 0.1 mg/L free chlorine residual led to taste and odor complaints, chlorination was discontinued, and water that contained no residual was distributed. Shortly after this change, samples with higher retention times produced HPCs as high as 60–80 cfu/mL. After four to six weeks these counts decreased to values again < 5 cfu/mL. This short‐term increase in HPCs, which has also been observed in other cases, is assumed to be due to a change in the biofilm.