By Kelly A. Reynolds, MSPH, Ph.D.
At a minimum, state health departments recommend monitoring private water supplies for bacteria, nitrates and nitrites annually and arsenic, uranium, radon, lead and fluoride every three to five years. To ensure proper testing and quality assurance/quality control, laboratories certified by the United States Environmental Protection Agency (US EPA), state and/or national accreditation programs are preferred. Although widely available, US consumers frequently opt out of routine monitoring of their individual water supplies. For much of the population in the developing world, however, such services are neither available nor affordable. Low-cost, user-friendly bacterial test kits are needed for water quality monitoring in the developing world and are expected to have a major impact on disease and death rates by helping people recognize when water sources are unsafe to drink or require treatment. These global initiatives serve to remind us of the importance of contaminant monitoring and treatment at the point of use (POU) to ensure the best quality water.
Saving lives around the world
Deaths due to waterborne infections (i.e., diarrhea) are estimated at 1.8 million per year globally. Most of these deaths (1.5 million) occur in children under the age of five.1 World Health Organization estimates that 94 percent of diarrhea cases are preventable through improvements in water quality, sanitation and hygiene. In recent decades, there has been a dramatic decrease in diarrhea deaths due to the global introduction of oral rehydration treatments, with an estimated 40 million lives saved since 1979. The oral rehydration therapy intervention has been called one of the most significant medical advances of the 20th century.
More recent advances in water quality maintenance are focused on ensuring that source water and POU water supplies are safe to drink. In November of 2007, an international consortium led by the University of Bristol (UK) released information on a product under development called Aquatest. Aquatest is reported to be “the world’s first low-cost, easy-to-use diagnostic tool giving a clear, reliable indication of water quality”.
Similar to the colorimetric tests used in the US to monitor municipal water supplies for the presence of E. coli (a fecal indicator bacterium), Aquatest is being designed as a small, hand-held, single-use device that requires no electricity, incubation or technical expertise to operate (see prototype design at www.bristol.ac.uk/aquatest/media/pressimates/device-large.jpg). A 100-milliliter water sample is simply added to the container and automatically divided into 10 separate tubes. After 24-36 hours of incubation at ambient temperature, a distinct color change indicates the presence of a minimum of 10 E. coli colony forming units in the 100-milliliters of water. Considered a marker of fecal contamination, water that tests positive for E. coli is not safe for consumption. The more tubes that test positive, the more contaminated the sample.
Aquatest is being designed for use in developing countries at an estimated cost of US $0.10 per test. Water sanitation engineers/advisors are expected to use the device to manage shared water supplies while individual consumers will be able to test their own water and evaluate treatment needs at the point of use.
The first phase of Aquatest was a preparatory project aimed at identifying various criteria for the diagnostic test. Now in the second phase of development and with increased funding from the Bill & Melinda Gates Foundation (US $13 million), the international research consortium plans to move forward into the full research and development phase. Phase two is expected to extend from 2007-2011 toward the eventual goal of widespread use of Aquatest in 80 percent of developing countries within the next 10 years (www.prweb.com/releases/bristol/university/prweb569101.htm).
Groundwater contamination in the US
Improved water quality monitoring in the developing world is expected to reduce illness and deaths by informing consumers of contaminated water supplies to be avoided or treated prior to consumption. The developers of Aquatest point out that if even 10 percent of water-related deaths are avoided with increased monitoring and surveillance, as many as 180,000 lives could be saved.
Although deaths due to waterborne pathogens are relatively rare in the US, improved drinking water quality can be expected to reduce the illness incidence in developed countries. In the most recently published survey period (2003-2004), contaminated groundwater was associated with seven times more (n = seven) waterborne disease outbreaks than surface water (n = one).2 Of the documented outbreaks, 51 percent (17/33) were associated with water supplies that were not under the jurisdiction of a water utility (i.e., private water supplies and commercially bottled water). In the previous survey period (2001-2002), 92 percent (23/25) of outbreaks associated with drinking water were from a groundwater source and 39 percent (nine) of these were associated with individual homeowner systems not regulated by the US EPA.3
It is well known that many more cases of waterborne disease are not reported in the US. In fact, researchers estimate that the total number of waterborne illnesses per year in the US is 19.5 million. Of these, 5.4 million illnesses per year occur in populations served by community groundwater systems and 1.1 million illnesses per year occur in non-community groundwater systems.4 Recent surveys and risk estimates support the promulgation of the Ground Water Disinfection Rule by the US EPA in October of 2006, requiring increased monitoring and assurance of groundwater quality and vulnerability assessment as well as corrective action requirements. The Ground Water Disinfection Rule, however, applies to municipal water supplies currently regulated by the US EPA and offers no additional safeguards to homeowners with private or individual water supplies.
Routine monitoring of water supplies is important to accurately evaluate the safety of water for consumption. Per sample costs for private water supply monitoring can range from about $15 for single-contaminant monitoring (i.e., lead only) to hundreds of dollars for multi-contaminant monitoring (i.e., select pesticides, metals and bacteria). For many, POU water purification devices offer significant safeguards protecting consumers from contaminants that may be present in their water supplies whether the contamination potentially occurred during distribution from a municipal treatment plant or from unregulated, private water supplies that are not as extensively monitored. The development of low-cost methods for monitoring the presence of fecal contamination in some of the world’s most polluted water promises to reduce the mortality rate of waterborne disease globally and in the absence of advanced water treatment technology. While adverse health outcomes are less severe in developed countries, it is important to identify contaminant exposures in order to determine appropriate treatment actions.
References and additional information
- WHO, 2004. World Health Report (Geneva, World Health Organization)
- Liang, J.L., et al. (2004) Surveillance for waterborne disease and outbreaks associated with drinking water and water not intended for drinking–United States, 2003-2004. MMWR 55(SS-12): 31-68.
- Blackburn RS, et al. (2004) Surveillance for waterborne-disease outbreaks associated with drinking water–United States, 2001-2002. MMWR 53(SS-8):23-45.
- Reynolds, K.A., et al. 2007. Risk of waterborne illness via drinking water in the United States. Reviews in Environmental Contamination & Toxicology. 192:117–158.
- The University of Bristol. Water and Health Research Centre, Institute for Advanced Studies. www.bristol.ac.uk/aquatest/media
- Center for Environmental Quality, Wilkes University, Wilkes-Barre, PA. www.water-research.net/homeowner.htm
About the author
Dr. Kelly A. Reynolds is an associate professor at the University of Arizona College of Public Health. She holds a Master of Science Degree in public health (MSPH) from the University of South Florida and a 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 at firstname.lastname@example.org