Point-of-Use Drinking Water Devices for Assessing Microbial Contamination in Finished Water and Distribution Systems

Abstract

The objective of this study was to develop a method to monitor the microbial quality of treated drinking water at the tap utilizing point-of-use filter systems that are placed in water vending machines. Such vending machines have high-volume water throughput and allow for an evaluation of the occurrence of human enteric pathogens and fecal indicator bacteria in tap water over extended time periods. Seeded experiments, using Escherichia coli and bacteriophage MS-2, were performed on (i) new filters, (ii) artificially aged filters, and (iii) filters that had been used in the field (naturally aged filters) to evaluate the efficiency of recovery of these organisms from the three-component filter set (30 microm, 5 mirom, solid block carbon (SBC)) by evaluating each filter independently. SBC filters had the highest recovery of the organisms, averaging recovery of 27% and 5% for E. coli and MS-2, respectively. Subsequently, tapwatersupplieswere monitored in vending machinesthroughout Southern Arizona using SBC filters as a monitoring tool. A total of 48 filters from 41 unique site locations were surveyed for the presence of total coliforms, E. coli, enterococci, Cryptosporidium, enteroviruses, and noroviruses. Organisms were detected following the passage of large volumes of water ranging from 1000 to 17,000 L through the filters. Out of 48 SBC filters 54.2% were positive for at least one organism. The number of filters positive for total coliforms, E. coli, enterococci, and enterovirus was 13, 5, 19, and 3, respectively, corresponding to 27.1%, 10.4%, 39.6%, and 6.3% of the total filters. No filters were positive for noroviruses or Cryptosporidium. These results suggest that the SBC filter can be used to monitor large volumes of treated drinking water and detect the incidence of indicators and pathogens that may be present at low concentrations. These data show that post-treated water often contains water quality indicator and pathogenic organisms at the tap, and therefore, monitoring with this method would be beneficial to the community as it allows for an assessment of exposure to pathogens and associative risks. This monitoring tool will also aid in the tracking of outbreaks and the determination of the microbial pathogen load during all stages of an outbreak as a filter can be installed and retrieved at the point-of-use at anytime during an outbreak.

Ag colloids and Ag clusters over EDAPTMS-coated silica nanoparticles: synthesis, characterization, and antibacterial activity against Escherichia coli

“…Outbreaks of E. coli O157:H7 infection have been associated with the consumption of foods of animal origin, such as undercooked beef, 8 improperly pasteurized milk, 9 or contaminated water. 10 It is estimated that these bacteria cause thousands of foodborne illnesses and hundreds of hospitalizations and deaths worldwide each year. 11 It is very important to monitor pathogenic E. coli strains and stop their growth by simple and novel means.…”

Point‐of‐Use Devices for Attenuation of Trace Organic Compounds in Water

“…This study demonstrated that POU devices have the ability to reduce the concentration of a diversity of emerging organic chemical contaminants in potable water, complementing the removal of metals, inorganics, and microbes researched by others (Sato et al 2011, Deshomes et al 2010, Miles et al 2009). Furthermore, these devices provide an additional barrier to accidental or intentional contamination that may occur in the distribution system, such as cross-connections, loss of pressure, or acts of terrorism (Zhong et al 2012).…”

“…A POU treatment device is any unit that is designed to improve water quality by providing a barrier against both microbial and chemical contaminants in water within a home (Mintel 2011, Miles et al 2009, Sobsey et al 2008, Esrey et al 1991. Several configurations of POU devices are commercially available, and technologies within a POU type device can be configured for a particular water quality.…”

Biological approaches for addressing the grand challenge of providing access to clean drinking water

“…Recent studies on over 500 wells around the U.S. showed that 10-42% of groundwater supply wells are contaminated with enteric viruses [10]; 95% of all individual and small groundwater systems violate one or more primary and secondary drinking water standards in Arizona [11]; and 52% of all point-of-use carbon filters contain an enteric organism after 3 months of use in a municipal system [12]. Approximately 80% of consumer complaints about tap water quality originate in the consumer's home distribution system [4], indicating that management of water quality problems cannot easily be addressed from a single central location.…”