Reverse osmosis (RO) water filtration reduces the dissolved contaminants in water, yielding more pure and healthy drinking water, but is this process alone adequate to ensure safety? In some applications, a combination of treatment types is preferred.

U.S. drinking water

The drinking water supply in the U.S. is far better than in many countries, and all public systems are required to follow the U.S. Environmental Protection Agency’s standards. However, municipal facilities’ systems are vast and aging with many potential contamination points.

Though rare, boil water notices are issued, and some outbreaks of illness related to drinking water contaminants occur. In addition, faucets are increasingly cited as a source of pseudomonas and Legionella. Organizations within the water industry are constantly working to improve filtration and sanitization methods (from product designers and engineers to installers).

POU treatment

By filtering and purifying water at the point of use (POU), verifiable advantages are achieved, including the following:

  • Cost savings
  • Ease of use
  • Strong environmental benefits when compared to a traditional bottled water cooler

Most RO systems are effective at removing some of the worst water contaminants, such as arsenic, lead, pesticides and cysts. While the semipermeable membrane serves as an excellent barrier, the pore size may grow and membranes become fouled with time as contaminants are continually pressed against it. According to the Food & Drug Administration, “It has been reported that bacteria can ‘grow’ through membranes.”1

In addition, other points of possible contamination following RO filtration continue all the way to the faucet. This is why end users need a solution at this location for a final barrier.

UV disinfection

Recent technology provides a solution for the final barrier right at the point of dispense. This technology is 99.9999 percent effective against microbes 100 percent of the time, according to independent laboratory tests. It treats water with ultraviolet (UV) purification milliseconds before it exits the tap into a container and stops back contamination from outside the tap. While UV systems are not new, recent breakthroughs have allowed the UV treatment to be positioned directly at the faucet, and the system provides such an intense UV dose that the system is certified to American National Standards Institute (ANSI)/NSF 55a for UV treatment systems and ANSI/NSF P231 for microbiological purification. The benefit of such an intense UV at the faucet is not only the water purification but its ability to sanitize the faucet.

Tap water or traditional water fountains may contain contaminants including pathogens such as pseudomonas, Legionella, streptococcus and E. coli. Point of dispense UV technology can guarantee that water is free from microorganisms (bacteria, viruses and fungi), contaminants and chlorine. If a sudden outbreak of bacteria or viruses in the local water supply occurs, this technology will eliminate the contaminant. If the faucet becomes contaminated by the end user (for example, from dirty hands, which probably cause the most outside contamination), UV technology also purifies the nozzle to 99.9999 percent.

faucets, pseudomonas aeruginosa, UV, contaminants

Table 1. The occurrence of pseudomonas aeruginosa in faucets

The American Journal of Infection Control ( recently published findings from Dr. Charles Gerba about how the effective use of UV light within the faucet eliminates pseudomonas aeruginosa in drinking water. The potential presence of any pseudomonas aeruginosa or other waterborne pathogens is a major concern, especially in health care environments.

The study evaluated the presence of pseudomonas aeruginosa in drinking water by testing tap water, water treated with a POU activated carbon filter unit and water treated with the UV technology. As shown in Table 1, the UV technology resulted in 0 percent of pseudomonas aeruginosa at the tap.

Materials of construction

Another level of protection that POU drinking water systems can use is incorporating silver into key components and surfaces. Silver is a natural antimicrobial that inhibits the growth of microorganisms. Using this material of construction can provide additional surface protection from microbes that may colonize and lead to the spread of germs.


A combination of RO, UV sanitization and antimicrobial materials of construction serve as a final barrier. Look for systems certified by the Water Quality Association to ANSI/NSF 55a for UV treatment.

Better still are systems certified as a microbiological purifier to the protocol ANSI/NSF P231 for the most protection for drinking water.


Photo courtesy of WaterLogic

Photo courtesy of WaterLogic


Lisa VanWyngarden is senior marketing manager for Waterlogic USA. She may be reached at Waterlogic is a designer, manufacturer, distributor and operator of mains-attached POU drinking water purification and dispensing systems designed for environments such as offices, factories, hospitals, hotels, schools, restaurants and other workplaces. For more information, visit