Water Conditioning & Purification Magazine

UV Disinfection: Coming of Age in the Residential Market

By Diane Arnott and Anthony Oosterveld

POU water disinfection is quite familiar to campers and hikers, who recognize that even a pristine-looking lake or stream can be carrying contaminants. These contaminants range from sediment to harmful microorganisms like bacteria and cysts that can cause severe illness. Convention would tell us that prior to drinking from surface-water sources, the water needs to be filtered and then boiled or held at length in a clear container exposed to the sun to make it safe. In other words, it needs to be disinfected. Another disinfection option is to add chlorine, which can also eliminate the risk of illness. More recently, however, additional UV disinfection options for outdoor enthusiasts have become available, such as a hand-held UV device and water bottles with built-in UV technology that deliver a chemical-free process for achieving safe drinking water.

Beyond roughing it in the woods, POU disinfection also is popular and appropriate for RVs and boats. For these applications, the safety of supplied water should be considered with caution, because it is often sourced from the smallest of public water supplies in the US, those that struggle most with meeting US EPA regulations. In fact, waterborne disease outbreaks are more commonly associated with seasonal water systems, like campgrounds or those systems that see infrequent use.(1) Compounding the risk is the fact that water supplies are often held in tanks aboard recreational vehicles that under the right conditions could provide an environment for microbial growth. POU water treatment, including UV disinfection, is a natural fit, especially considering a POU-UV device has a very small footprint, requires little maintenance and eliminates the need to transport or handle chemicals.

Residential UV use gaining ground

But what about at home? Is there some doubt about the quality and safety of water? Municipalities, especially the larger ones, invest heavily in ensuring the quality of the water they produce and on the whole, the results are admirable, with few reported water quality infractions. Researchers are finding, however, that the water leaving the treatment facility is markedly different than that which comes out of the household tap, particularly in regard to the microorganisms present. As a result, a POU-UV device can be added insurance for safe drinking water, especially in apartments or condos where there may not be treatment at the point of entry to the building itself.

The need for water treatment in apartment buildings was highlighted in a 2014 story by The New York Times, “Inside City’s Water Tanks, Layers of Neglect.” Water supplies for apartment buildings that exceed six stories, especially older ones, are stored in on-site tanks and then pumped to individual units. There are some 12,000-17,000 of these buildings and, according to a city survey, 60 percent of owners reported that they do not comply with regulations concerning the maintenance, inspection and water testing of the tanks. Independent testing of some of these tanks revealed the presence of coliforms, in some cases E.coli. Though samples were drawn from the bottom of the tanks, below the pipe that supplies the apartments, these findings are cause for concern. And New York is by no means the only city employing water tanks.

Apartment residents are not the only ones facing increased risk of bacterial contamination in their home water supply. Water flowing through countless miles of pipes after leaving the treatment facility is a recognized risk, hence the mandated chlorine residual for potable water supplies. Those pipes, however, are aging and deteriorating, which results in homeowners being exposed more frequently to potential contamination. Between 2012-2014, there were nearly 21,000 boil-water advisories (BWA) issued in the US; the majority were due to leaks or breaks in a pipe or water main (53 percent) and another 14 percent caused by low-pressure events.(2) After a BWA event, consumers have generally fallen back on familiar POU water treatment, such as pour-through filters or faucet-mounted devices. In fact, according to a recent survey by the Water Quality Association (WQA), some 40 percent sought these solutions. (Ironically, it is the chlorine in public water supplies that makes these particular products so familiar.) Homeowners have been driven to POU treatment devices to manage the objectionable taste and odor of chlorine.

In the water treatment industry, the adsorption ability of activated carbon is well recognized for color, taste and odor (CTO) reduction, but it is also recognized for its potential to harbor and promote the growth of microorganisms. This can present a risk to homeowners who self-select the familiar and may be oblivious to the fact that these so-called tried-and-true solutions alone may not be right for them. For the homeowner looking to manage aesthetic concerns like eliminating chlorine taste or discoloration in city water, a carbon filter is a suitable choice, but to ensure the bacteriological safety of the water, POU UV should also be added. Water treatment devices using other media or a membrane for chemical reduction or particulate removal will require cleaning or replacing after a BWA event because those technologies are not designed for use on microbiologicaly unsafe water. POU UV, however, can ensure safe water even when this type of maintenance is overlooked. Finally, UV provides protection from a broad range of microorganisms, including protozoan cysts and viruses, making UV the perfect addition to existing POU technologies (like RO) in a multibarrier strategy to deliver safe drinking water at the tap.

The good. UV is an effective means of disinfection that requires no chemicals, which is critical when disinfection is used with products like reverse osmosis, where the fundamental function is chemical removal. UV is very scalable; it can be easily engineered for any application and supplied at an economical price. Additionally, UV is capable of inactivating organisms that are resistant to traditional chemicals like chlorine.

The bad. Most UV systems are designed for continuous operation, meaning they are on even when there is no water demand. This can produce a negative perception of their impact to energy costs. In reality, the energy draw of a typical UV system is minimal; however, the heat produced and transferred to the first bit of water dispensed can be an annoyance. Unfortunately, the redress applied to avoid the ‘hot water shot’ with POE UV—adding a dump valve or a cooling fan—are impractical for POU-UV devices, as they are most frequently installed in confined spaces with no available drain. Thus, the homeowner’s only recourse is to be aware of the risk and allow the water to run prior to use. While not ideal, the water waste is minimal as the volume of a POU-UV device is low.

The future. UV manufacturers are doing amazing things with mercury lamps, lamp filaments and ballast designs to drive significant innovation, like power-cycling mechanisms and lamp-dimming to simulate an instant-on effect. Improvements like these in the POE segment may, in time, see application in POU, as well addressing many of the current limitations of POU-UV application. The introduction of UVC LED is something of great interest to many. At present, however, output efficiencies are making these somewhat costly, but they have the potential to change the landscape of POU disinfection devices.

Conclusion

As the media continues to drive awareness of water quality issues, more and more consumers will seek to take ownership of the quality and safety of their drinking water. UV disinfection, be it POU or POE, needs to be leading the charge.

References

  1. Pons W., Young I., Truong J., Jones-Bitton A., McEwen S., et al. (2015). A Systematic Review of Waterborne Disease Outbreaks Associated with Small Non-Community Drinking Water Systems in Canada and the United States. PLOS ONE 10(10): e0141646.
  2. Reynolds, Kelly A. (2016) Boil Water Notices in the U.S. 2012-2014. Zuckerman College of Public Health, University of Arizona. Tucson, AZ.

About the authors

Diane Arnott, B.Sc. (Marketing Research) has a background in consumer packaged goods and the healthcare industry as a brand manager. She has over a decade of experience leveraging consumer insight to drive business. Arnott, who is passionate about voice of customer, can be reached at darnott@viqua.com.
Anthony Oosterveld (Business Development Manager, Regulated Markets of VIQUA) is a 14-year veteran of the company and has held many roles within the organization, mostly in a technical capacity. He’s been responsible for focusing on small public water systems within North America, working closely with state, provincial and regulatory bodies to train and educate clients on the benefits and applicability of UV technologies for regulatory compliance. Oosterveld is currently a member of VIQUA’s Senior Leadership Team, which is responsible for the strategic direction of the organization. He can be reached at aoosterveld@viqua.com.

About the company

VIQUA (formerly R-Can Environmental) specializes in the engineered design and development of residential, light-commercial ultraviolet disinfection systems and is a proud member of the Water Quality Association (WQA) and International Ultraviolet Association (IUVA).

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