By Kelly A. Reynolds, MSPH, Ph.D.
Isn’t my water safe enough? What level of water treatment do I need? Why are some POU treatment devices so expensive? These common questions from consumers contemplating home water treatment options exemplify three major issues facing the POU industry today:
- To prove a health benefit to POU water treatment;
- To identify uncontrolled pathogen exposure routes (POU or POE); and
- To justify (or minimize) cost.
As an industry, it is important to be informed of the risks of waterborne disease and to be able to inform the consumer about balancing the benefits of home water treatment against the costs.
Waning consumer confidence
Consumers are steadily losing confidence in the quality of their drinking water, according to a survey by the Water Quality Association (2004).1 The survey reports that 64 percent of Americans are concerned about the quality of their water, while nearly half feel their drinking water is not as safe as it should be. Media headlines of outbreaks, boil-water notices and environmental pollution concerns continue to impact public concern of water quality. This concern likely contributes to the increasing sales of POU treatment systems and bottled water. While it is clear that consumers are willing to pay more for better drinking water, there is a huge disconnect on what technologies are needed to produce better water.
From a scientific standpoint, there are significant data gaps regarding exposure to waterborne pathogens. Pathogen monitoring data, at the point of use is sparse and an extensive, broad-spectrum survey of various geographical regions in the U.S. is needed. Unknown (to date) is the risk of exposure to pathogens in drinking water over extended periods of time, as well as the various routes of exposure and the potential risk reduction benefit that could be realized from the use of a POU drinking water treatment system. The following is a discussion of these major data gaps in POU water treatment needs.
Data gap 1: POU water treatment benefits
Generally, it is not difficult to convince the consumer that POU water filtration can improve the taste and odor of drinking water. Filters designed to improve these qualities are typically inexpensive, widely available and easily installed. POU treatment systems, particularly those targeting a wide range of harmful chemicals or microbial pathogens (human viruses, cryptosporidia, etc.), tend to be more costly and require professional installation and maintenance. The first obstacle for the POU industry to overcome with the consumer is that a filter designed to improve taste and odor does not necessarily improve the water quality with regard to public health-related contaminants.
The second obstacle for the POU industry is to justify the need for more extensive (and expensive) home water treatment. Although we know waterborne disease outbreaks occur each year and that disease associated with water is largely underreported, little information is available regarding the relative risk of drinking tap water versus treated water in the home. A recent study of more than 1,200 volunteers from 456 homes was conducted to try and close this data gap.2 Half of the homes were given a placebo unit while the other half were supplied with POU treatment devices utilizing one-micron filtration and ultraviolet light disinfection. Volunteers kept weekly health diaries, tracking their drinking water consumption and gastrointestinal illness. Result: there was no significant difference in health symptoms between the two groups. However, the treatment plant studied, reportedly surpassed all water quality standards and is known to have a high quality distribution system, which is not the case for all U.S. water treatment and distribution systems. What if your water receives no treatment, comes from a private well or is subject to intrusion events in an aging distribution system?
In order to address these concerns, information is still needed regarding:
- The quality of tap water in various regions of the United States, including municipal and private water sources;
- The assessment of exposure risks and potential acute and chronic health effects associated with occurrence levels of specific contaminants; and
- The level of POU treatment needed to eliminate specific contaminants to achieve a measurable health benefit.
Data gap 2: Validating important waterborne pathogen exposure routes
Recent outbreaks from bath water exposures to pathogens (i.e., the deadly Naegleria) and the reported risks of shower aerosols to immunocompromised populations (i.e., illness from Legionella pneumophila, Mycobacterium avium complex) support the need for expanded POU treatment in the home. Because toilet, irrigation and laundry wash water may not need to be of the same quality as shower, bath and drinking water sources, home treatment systems may be required that serve varying needs at various exposure sites. Therefore, research is needed focusing on exposures via waterborne routes in the home, other than through drinking water. Further, specific technologies and POU systems need to be evaluated for their ability to control these exposures considering known resistance of some microbes to conventional treatment and their ability to grow in home plumbing or other post-treatment distribution systems.
Risk analysis is needed for both immunocompetent and immunocompro-mised populations, since the latter are more susceptible to adverse outcomes associated with microbial infections. Such analysis would aid in the evaluation of POU treatment levels needed for risk reduction relative to various exposure routes. Varying technologies for point of use treatment, (i.e, granular activated carbon versus submicron filtration versus ozone disinfection, etc.) need to be considered for different exposure routes in the home in order to evaluate the most appropriate treatment level for controlling the most likely contaminants present.
Simplifying POU treatment
The bottom line is that consumers want higher quality water and they desire low cost, easy to use POU water treatment devices that can improve water quality beyond just taste and odor. Until treatment costs can be minimized, however, they must be justified. Unfortunately, the true incidence of waterborne disease and the benefit of POU water treatment still need to be determined in controlled, scientific and unbiased studies. Such studies must be conducted in consideration of geographical variation in source water quality and contaminant occurrence, treatment differences, changes in distribution system integrity and susceptibility variances in exposed populations. A final challenge for the industry is to communicate exposure and risk information to the consumer in conjunction with the availability of effective treatment solutions.
- WQA. 2004 WQA Consumer Attitudes Survey. August 16, 2004. Press release: http://www.wqa.org/pdf/Pressreleases/PR-2004ConsumSurvey-.pdf
- Yang, S., Home-treated Water No Better than Plain Tap in Preventing Gastrointestinal Illness, Finds New Study, University of California-Berkeley, Sept. 25, 2003: www.berkeley.edu/news/media/releases/2003/09/25_water.shtml
About the author
Dr. Kelly A. Reynolds is a research scientist at the University of Arizona with a focus on development of rapid methods for detecting human pathogenic viruses in drinking water. She holds a master of science degree in public health (MSPH) from the University of South Florida and doctorate in microbiology from the University of Arizona. Reynolds has been a member of the WC&P technical review committee since 1997. She can be reached via email, firstname.lastname@example.org