Microbial proliferation relates to the species present in the tap water in the filter devices, the presence or absence of a free-chloride residual, seasonal changes in water temperatures, ambient air temperatures around the device and the service duration for a given carbon cartridge.
Static water conditions overnight or for longer intervals provide an opportunity for continued growth of drinking water microorganisms colonizing the carbon filters. Ambient air temperatures that translated into static water temperatures, coupled with available nutrients in the carbon particles and no flushing, are the prime factors favorable to increase the growth of microbes in drinking water i.e., the heterotrophic plate count (hpc) heterotropic bacteria.
The occurrence of drinking water pathogens like the pigmented bacteria (forming yellow, organic pink, brown, or black colonies) often found in treated distribution water, will be potentially useful markers in interpreting the changes in the microbiological quality of the product water from the house treatment devices.
On the basis of the data presently available in various tests, it is understood that most of the drinking water pathogens or opportunistic bacteria will generally not colonize and or be present for long in the carbon filter devices that already have bio-film population of non-pathogenic heterotropic bacteria. However, source organisms such as k.preamoniae, a.hydrophila and l.prevnophila can colonize and could prove to be drinking water health hazards for some consumers.
Miscellaneous methods and its applications
Point-of-use methods for reduction or removal of drinking water pathogens and other contaminants in water supply:
Method / water treatment devices (WTD)= Filtration -> General removal applications = Turbidity, particulates, color
Method / WTD = Adsorption -> General removal applications = Chlorine, organic substances, odors
Method / WTD = Ion exchange Cationic Anionic -> General removal applications = Calcium, mercury, magnesium iron arsenic, selenium
Method / WTD = Distillation -> General removal applications = Inorganic substances, dissolved solids
Method / WTD = Reverse osmosis -> General removal applications = Metals, total dissolved solids
Method / WTD = Water softening -> General removal applications = Barium
Method / WTD = Lime softening -> General removal applications = Cadmium
Method / WTD = Water porifiers, Filtration barrier, Disinfection barrier -> General removal applications = Giardiamunis or giandia camblia bacteria, viruses.