Tap water filtering devices are widely employed to improve odor and taste of tap water, or to obtain refrigerated or sparkling drinking water. The presence of disinfectants-resistant bacteria in tap water is responsible of the biofilm formation inside tubes and tanks. The consequent contamination of dispensed water is a well-known hygiene problem because of the quite constant presence of potentially pathogenic bacteria likes P. aeruginosa. In this study, we tested the technical feasibility and effectiveness of the addition to different commercial devices of a packaged polysulphone fibers filter. We aimed to find a simple solution to implement the quality of the delivered water. Water contamination levels were determined in a wide selection of microfiltered water dispensers and we selected among them a representative group of 10 devices, new or in use. The packaged ultrafilter was introduced in about half of them, to monitor, when possible, in parallel the contamination levels and flow rate of a couple of identical units, with and without the filter. The placement of the dialysis filters resulted feasible at different positions along the water circuits of the variously designed filtration units. Delivered water resulted completely free from bacteria when the filter was placed exactly at, or very close to, the outlet in spite of the inner surfaces contamination. This performance was not obtained in presence of a more or less long tract of water circuits downstream the ultrafilter: a significant but not complete reduction of the plate count numbers was observed. The filters worked in continue over the whole study period, ten months, showing exactly the same efficiency. Moreover, the flow rate in presence of the filter was quite unaffected. The addition of this kind of filter to already in use water dispensers was technically easy, and its use can be recommended in all cases a simple but reliable water sanitization is requested.
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. J.T. Walker P.D. Marsh Microbial biofilm formation in DUWS and their control using disinfectants. Journal of Dentistry 35 721-730 (2007).
. P.G. Mazzola A.M.S. Martins T.C.V. Penna Chemical resistance of the Gram-negative bacteria to different sanitizers in a water purification system. BMC Infectious Diseases 6 131-141 (2006).
. S.A. Abdallah A.I. Khalil Impact of cleaning regimes on dental water unit contamination. Journal of Water Health 9 647-652 (2011).
. A. Culotti A.I. Packman Pseudomonas aeruginosa promotes Escherichia coli biofilm formation in nutrient-limited medium. PLoS ONE 9 (9): e107186 (2014). Doi:10.1371/journal.pone.0107186.
. R. Sacchetti G. De Luca A. Dormi E. Guberti F. Zanetti Microbial quality of drinking water from microfiltered water dispensers. International Journal of Hygine and Environmental Health 217 255-259 (2014).
. K. Todar. Pseudomonas aeruginosa. Online textbook of Bacteriology. Kennet Todar University of Winsconsin Madison Department of Bacteriology (2008). http://www.textbookofbacteriology.net Last accessed: July 2016.
. European Council. Directive 98/83/EC on the quality of water intended for human consumption. Official Journal EU L 330 32–54 (1998).
. A. Baumgartner M. Grand Bacteriology quality of drinking water from dispensers (coolers) and possible control measure. Journal of Food Protection 69 3043-3046 (2006).
. I.F. Chaberny P. Kaiser H.-G. Sonntag Can soda fountains be recommended in hospitals? International Journal of Hygiene and Environmental Health. 209 471-475 (2006).
. G. Liguori I. Cavallotti A. Arnese C. Amiranda D. Inastasi I.F. Angelillo. Microbiological quality of drinking water from dispensers in Italy. (2010) BMC Microbiol. Open Access Research Article available at: http://www.biomedcentral.com/1471-2180/10/19. Last accessed: July 2016
. R. Sacchetti G. De Luca F. Zanetti Control of Pseudomonas aeruginosa and Stenotrophomonas maltophilia contamination of microfiltered water dispensers with peracetic acid and hydrogen peroxide. International Journal of Food Microbiology 132 162-166 (2009).
. F. Zanetti G. De Luca R. Sacchetti Control of bacterial contamination in microfiltered water dispensers (MWDs) by disinfection. International Journal of Food Microbiology 128 446-452 (2009).
. F. Zanetti G. De Luca E. Leoni R. Sacchetti Occurrence of non-fermenting gram-negative bacteria in drinking water dispensed from point-of-use microfiltration devices. Annals of Agricultural Environmental Medicine 21 29-34 (2014).
. K.Y. Nelson D.W. McMartin C.K. Yost K.J. Runtz T. Ono. Point of use water disinfection using UV light-emitting diodes to reduce bacterial contamination. Environmental Science Pollution Research 20 5441-5448 (2013).
. M. Garvey D. Rabbitt A.N. Rowan. Pulsed ultraviolet light inactivation of Pseudomonas aeruginosa and Staphylococcus aureus biofilms. Water Environmental Journal 29 36-42 (2015).
. C.G. Okpara N.F. Oparaku C.N. Ibeto. An overview of water disinfection in developing countries and potentials of renewable energy. Journal of Environmental Science Technology 4 18–30 (2001).
. Watercoolers Europe Association (2011). Standard Methodology for the Examination of Dispensed Water of point of use & point of entry Water Coolers installed inside buildings. Available at: www.watercoolerseurope.eu. Last accessed: July 2016.
. L. Bonadonna M. Ottaviani. Reference analytical methods for water intended for human consumption according to the Italian Legislative Decree 31/2001. Microbiological methods. Report of Istituto Superiore di Sanità - Rapporti ISTISAN 07/5 (2007). (in Italian) Available at: www.iss.it Last accessed: July 2016.
. International Organization for Standardization. ISO 7899-2 Water quality Detection and enumeration of intestinal enterococci—Part 2: Membrane filtration method (2003). Available at: http://www.iso.org/iso/home/standards.htm Last accessed: July 2016.
. American Public Health Association. Standard Methods for the Examination of Water and Wastewater 21st edition. Washington DC: APHA (2005).