Use of HPC in water management
HPC testing has a long history of use in water microbiology. At the end of the
19th century, HPC tests were employed as indicators of the proper functioning
of processes (and of sand filtration in particular) and thereby as indirect
indicators of water safety. Use as a safety indicator declined with the adoption
of specific faecal indicator bacteria during the 20th century.
HPC measurements nevertheless continue to figure in water regulations or
guidelines in many countries. HPC measurements are used:
• to indicate the effectiveness of water treatment processes, thus as an
indirect indication of pathogen removal;
• as a measure of numbers of regrowth organisms that may or may not
have sanitary significance; and
• as a measure of possible interference with coliform measurements in
lactose-based culture methods. This application is of declining value, as
lactose-based culture media are being replaced by alternative methods
that are lactose-free.