Nanoparticle and Transparent Polymer Coatings Enable UV-C Side-Emission Optical Fibers for Inactivation of Escherichia coli in Water.

Pathogenic bacteria pose a health threat and operational challenge in drinking water. UV-C light-emitting diodes (UV-C LEDs) are becoming a competitive disinfection technology but are limited by their small irradiation area. Side-emitting optical fibers (SEOFs) can serve as a UV-C LED light delivery technology for reactors or tubing. Modifying the surfaces of conventional optical fibers with scattering centers allows for side emission of 265 nm radiation from an LED for microbial inactivation in water. Solid-material absorbance and flux measurements differentiated light absorption from scattering for all materials. Silica spheres >200 nm in diameter achieved higher scattering than smaller silica. A critical discovery was that treating the silica-coated optical fiber in a solution of high ionic strength increased UV-C side emission by greater than 6-fold. Additionally, the cladding polymer Cytop had negligible absorbance at 265 nm wavelength. A scalable four-step treatment process was developed to fabricate the novel SEOF. Attached to a 265 nm LED, the side-emitting optical fiber achieved 2.9 log inactivation of Escherichia coli at a delivery dose of 15 mJ/cm2. The results illustrate proof of concept that UV-C SEOFs can inactivate E. coli and should be further explored for delivering LED light into water.

Copper nanoparticles toxicity: Laboratory strains verses environmental bacterial isolates.

Nanoparticles have emerged as significant environmental contaminants and their impact has been studied using laboratory strains of bacteria. This study focuses on investigating the response of environmental isolate and laboratory strains of E. coli to 50 and 100 nm size of copper nanoparticles (CuNPs). The laboratory cultures included pathogenic and non-pathogenic strains. The environmental isolate and the non-pathogenic E. coli strain showed different inactivation patterns. After 2 h exposure to 50 nm CuNPs, the environmental isolate and the lab strain of E. coli lost 7.22 and 6.47 log; whereas the reduction of 6.16 and 6.68 log resulted after exposure to 100 nm CuNPs, respectively. The pathogenic E. coli O157:H7 exposed to 50 and 100 nm CuNPs for 2 h resulted in 5.24 and 6.54 log reduction, respectively. Although the environmental isolate and the laboratory strains of E. coli showed similar inactivation trends; they exhibited different toxicity elicitation mechanisms after exposure to the CuNPs. The pathogenic and non-pathogenic strains elicited significantly different levels of glutathione reductase (GR) activities, an enzyme critical for protection against radicals. Similarly, the environmental isolate and the lab strains of E. coli exhibited opposite trend in GR activities. These results clearly indicate divergence in the toxicity elicitation in the environmental isolate versus the laboratory strains from exposure to CuNPs, which highlights the need for an in-depth investigation of the impact of NPs on the biological processes and long-term effect of high load of NPs on the stability of aquatic and terrestrial ecologies.

Stimulation of 2-methylisoborneol (MIB) production by actinomycetes after cyclic chlorination in drinking water distribution systems.

The impact of fluctuation in chlorine residual on actinomycetes and the production of 2-methylisoborneol (MIB) were studied in cast-iron and PVC model distribution systems. Actinomycetes were spiked in each system and continued operation for a 12-day non-chlorine experiment, resulting in no changes in actinomycetes and MIB concentrations. Three cyclic chlorination events were performed and chlorine residuals were maintained as follows: 1.0 mg L(-1) for 24 h, 0 mg L(-1) for 48 h, 0.5 mg L(-1) for 48 h, 0 mg L(-1) for 48 h and 2 mg L(-1) for 24 h. After each chlorination event, 2 -3 log decrease in actinomycetes was noted in both systems. However, within 48 h at 0 mg L(-1) chlorine, the actinomycetes recovered to the pre-chlorination levels. On the contrary, MIB concentration in both systems remained un-impacted after the first cycle and increased by fourfold (< 5 to > 20 mg L(-1)) after the second cycle, which lasted through the third cycle despite the fact that actinomycetes numbers fluctuated 2-3 logs during this time period. For obtaining biofilm samples from field, water meters were collected from municipality drinking water distribution systems located in central Arizona. The actinomycetes concentration in asbestos cement pipe and cast iron pipe averaged 3.1 × 10(3) and 1.9 × 10(4) CFU cm(-2), respectively. The study shows that production of MIB is associated with changes in chlorine residual in the systems. This is the first report of cyclic chlorine shock as a stimulus for MIB production by actinomycetes in drinking water distribution system's ecology.

A unified method to process biosolids samples for the recovery of bacterial, viral, and helminths pathogens.

For land application, biosolids are classified as Class A or Class B based on the levels of bacterial, viral, and helminths pathogens in residual biosolids. The current EPA methods for the detection of these groups of pathogens in biosolids include discrete steps. Therefore, a separate sample is processed independently to quantify the number of each group of the pathogens in biosolids. The aim of the study was to develop a unified method for simultaneous processing of a single biosolids sample to recover bacterial, viral, and helminths pathogens. At the first stage for developing a simultaneous method, nine eluents were compared for their efficiency to recover viruses from a 100 gm spiked biosolids sample. In the second stage, the three top performing eluents were thoroughly evaluated for the recovery of bacteria, viruses, and helminthes. For all three groups of pathogens, the glycine-based eluent provided higher recovery than the beef extract-based eluent. Additional experiments were performed to optimize performance of glycine-based eluent under various procedural factors such as, solids to eluent ratio, stir time, and centrifugation conditions. Last, the new method was directly compared with the EPA methods for the recovery of the three groups of pathogens spiked in duplicate samples of biosolids collected from different sources. For viruses, the new method yielded up to 10% higher recoveries than the EPA method. For bacteria and helminths, recoveries were 74% and 83% by the new method compared to 34% and 68% by the EPA method, respectively. The unified sample processing method significantly reduces the time required for processing biosolids samples for different groups of pathogens; it is less impacted by the intrinsic variability of samples, while providing higher yields (P = 0.05) and greater consistency than the current EPA methods.

Approaching easy water disinfection for all: Can in situ electrochlorination outperform conventional chlorination under realistic conditions?

Electrochlorination has gained research interest for its potential application as decentralized water treatment. A number of studies have displayed promising efficiency for water disinfection. However, a comprehensive comparison of in situ electrodisinfection to existing disinfection techniques, particularly under realistic water composition and flow rates, still needs additional research efforts. The aim of this study is to evaluate in situ electrochlorination while comparing the treatment with conventional chemical chlorination for point-of-entry decentralized disinfection at the household level. An electrochemical flow cell reactor was operated in a single pass mode considering water flow and water consumption for a household of four family members. Disinfection efficiency assessment of both electrochemical and chemical chlorination was conducted using bacterial and viral surrogates, E. coli and MS2 bacteriophage. Furthermore, a techno-economic analysis was conducted, using the levelized cost of water, to compare two electrochemical chlorination scenarios (i.e., electrical grid energy use, and solar panel powered system) and benchmarked against the baseline treatment of chemical chlorination. The findings revealed increased inactivation efficiency of in situ electrochlorination over conventional chlorination (p-value < 0.05). The synergetic impact of radicals and chlorine, and/or contribution of high chlorine concentration at acidic pH near anode surface were identified as key factors that could enhance disinfection performance of in situ electrochlorination. The techno-economic analysis demonstrated that electrochemical treatment, when operated using renewable energy sources, is not only a more environmentally sustainable approach, but also emerges as a more economically feasible solution for decentralized water treatment application. The results highlight that in situ electrochlorination is a more advanced alternative to decentralized water chlorination. However, further fundamental research on products and by-products formation under various water matrices is required.

Isolation of Bacteroides from fish and human fecal samples for identification of unique molecular markers.

Bacteroides molecular markers have been used to identify human fecal contamination in natural waters, but recent work in our laboratory confirmed cross-amplification of several human-specific Bacteroides spp. assays with fecal DNA from fish. For identification of unique molecular markers, Bacteroides from human (n = 4) and fish (n = 7) fecal samples were cultured and their identities were further confirmed using Rapid ID 32A API strips. The 16S rDNA from multiple isolates from each sample was PCR amplified, cloned, and sequenced to identify unique markers for development of more stringent human-specific assays. In human feces, Bacteroides vulgatus was the dominant species (75% of isolates), whereas in tilapia feces, Bacteroides eggerthii was dominant (66%). Bacteroides from grass carp, channel catfish, and blue catfish may include Bacteroides uniformis, Bacteroides ovatus, or Bacteroides stercoris. Phylogenic analyses of the 16S rRNA gene sequences showed distinct Bacteroides groupings from each fish species, while human sequences clustered with known B. vulgatus. None of the fish isolates showed significant similarity to Bacteroides sequences currently deposited in NCBI (National Center for Biotechnology Information). This study expands the current sequence database of cultured fish Bacteroides. Such data are essential for identification of unique molecular markers in human Bacteroides that can be utilized in differentiating fish and human fecal contamination in water samples.

Biochemical signature assay for use in a biosensor platform to detect bacteria in drinking water biofilms.

The objective of the study was to identify the enzymatic-biochemical (enz-bio) signatures of Escherichia coli and Salmonella for rapid detection of these bacteria in drinking water biofilms. The relative potency of lipophilic, glucosidic, and proteolytic activities in biofilms containing single bacterial species and mixture of different bacterial was used to identify the enz-bio signatures of Escherichia coli and Salmonella. The enz-bio signatures identified were: Lipophilic < Glucosidic < Proteolytic (for Escherichia coli); and Glucosidic = Lipophilic < Proteolytic (for Salmonella). The enz-bio assays were performed sequentially for detecting Escherichia coli and Salmonella in pure and mixed biofilm cultures formed on the coupons incubated in a batch reactor. The results obtained were substantiated by culture-based assays indicating comparable data. The enz-bio sensing method described here is a proof of principle and the results of this study provide a platform for the fabrication of a biosensor for bacterial detection in biofilms. The detection time required for the biosensor platform versus culture methods ranged from 10 to 120 min and 24 to 48 h, respectively.

Impact of Pipe Material and Temperature on Drinking Water Microbiome and Prevalence of Legionella, Mycobacterium, and Pseudomonas Species.

In drinking water distribution systems (DWDSs), pipe material and water temperature are some of the critical factors affecting the microbial flora of water. Six model DWDSs consisting of three pipe materials (galvanized steel, copper, and PEX) were constructed. The temperature in three systems was maintained at 22 °C and the other 3 at 32 °C to study microbial and elemental contaminants in a 6-week survey using 16S rRNA next-generation sequencing (NGS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). Pipe material and temperature were preferentially linked with the composition of trace elements and the microbiome of the DWDSs, respectively. Proteobacteria was the most dominant phylum across all water samples ranging from 60.9% to 91.1%. Species richness (alpha diversity) ranking was PEX < steel ≤ copper system and elevated temperature resulted in decreased alpha diversity. Legionellaceae were omni-prevalent, while Mycobacteriaceae were more prevalent at 32 °C (100% vs. 58.6%) and Pseudomonadaceae at 22 °C (53.3% vs. 62.9%). Heterogeneity between communities was disproportionately driven by the pipe material and water temperature. The elevated temperature resulted in well-defined microbial clusters (high pseudo-F index) in all systems, with the highest impact in PEX (10.928) followed by copper (9.696) and steel (5.448). Legionellaceae and Mycobacteriaceae are preferentially prevalent in warmer waters. The results suggest that the water temperature has a higher magnitude of impact on the microbiome than the pipe material.

Implication of cell culture methods and biases on UV inactivation of viruses.

Inactivation of human respiratory viruses in air and on surfaces is important to control their spread. Exposure to germicidal ultraviolet (UV-C) light damages viral nucleic acid rendering them non-infectious. Most of the recent viral inactivation studies have not considered potential artifacts caused by interactions between UV-C light and culture media used to suspend and deposit virus on surfaces. We show that the reactive oxygen and nitrogen species (ROS and RNS) form when commonly used virus culture media is exposed to 265 nm irradiation from light emitting diodes (LEDs) at UV-C doses (4 or 40 mJ/cm2) commonly considered to achieve multiple log-inactivation of virus. Surface viral inactivation values were enhanced from 0.49 to 2.92 log10 of viruses in DMEM, EMEM or EMEM-F as compared to absence of culture media (only suspended in Tris-buffer). The mechanisms responsible for the enhanced surface inactivate is hypothesized to involve photo-activation of vitamins and dyes present in the culture media, deposited with the virus on surfaces to be disinfected, which produce ROS and RNS. Given the rapidly growing research and commercial markets for UV-C disinfecting devices, there is a need to establish surface disinfecting protocols that avoid viral inactivation enhancement artifacts associated with selection and use of common cell culture media in the presence of UV-C light. This study addresses this weak link in the literature and highlights that inadequate selection of virus suspension media may cause a bias (i.e., over-estimation) for the UV-C dosages required for virus inactivation on surfaces.

Cell surface display of poliovirus receptor on Escherichia coli, a novel method for concentrating viral particles in water.

The lack of efficient methods for concentrating viruses in water samples leads to underreporting of viral contamination in source water. A novel strategy for viral concentration was developed using the expression of target virus receptors on bacterial cells. Poliovirus type 1, the most studied enterovirus, was used as a surrogate for enteric viruses. The human poliovirus receptor (hPVR) gene was expressed on the surface of Escherichia coli cells by using the ice nucleation protein (INP) gene. The hPVR gene was ligated to the 3' end of the INP gene after the removal of the stop codon. The resulting open reading frame (ORF) was used for the projection of hPVR onto the outer membrane of E. coli. Gene expression was tested by SDS-PAGE, Western blot, and dot blot analyses, and virion capture ability was confirmed by transmission electron microscopy. The application of engineered E. coli cells for capturing viruses in 1-liter samples of source and drinking water resulted in 75 to 99% procedural recovery efficiency. Cell surface display of viral receptors on bacterial cells opens a new prospect for an efficient and inexpensive alternative tool for capturing and concentrating waterborne viruses in water samples.

Legionella Occurrence beyond Cooling Towers and Premise Plumbing.

Legionella is an environmental pathogen that is responsible for respiratory disease and is a common causative agent of water-related outbreaks. Due to their ability to survive in a broad range of environments, transmission of legionellosis is possible from a variety of sources. Unfortunately, a disproportionate amount of research that is devoted to studying the occurrence of Legionella in environmental reservoirs is aimed toward cooling towers and premise plumbing. As confirmed transmission of Legionella has been linked to many other sources, an over-emphasis on the most common sources may be detrimental to increasing understanding of the spread of legionellosis. This review aims to address this issue by cataloguing studies which have examined the occurrence of Legionella in less commonly investigated environments. By summarizing and discussing reports of Legionella in fresh water, ground water, saltwater, and distribution system drinking water, future environmental and public health researchers will have a resource to aid in investigating these pathogens in relevant sources.

PCR inhibitor levels in concentrates of biosolid samples predicted by a new method based on excitation-emission matrix spectroscopy.

Biosolids contain a wide variety of organic contaminants that are known for their ability to inhibit PCR. During sample processing, these contaminants are coconcentrated with microorganisms. Elevated concentrations of these compounds in concentrates render samples unsuitable for molecular applications. Glycine-based elution and recovery methods have been shown to generate samples with fewer PCR inhibitory compounds than the current U.S. EPA-recommended method for pathogen recovery from biosolids. Even with glycine-based methods, PCR inhibitors still persist in concentrations that may interfere with nucleic acid amplification. This results in considerable loss of time and resources and increases the probability of false negatives. A method to estimate the degree of inhibition prior to application of molecular methods is desirable. Here we report fluorescence excitation-emission matrix (EEM) profiling as a tool for predicting levels of molecular inhibition in sample concentrates of biosolids.

Identification of microbial faecal sources in the New River in the United States-Mexican border region.

Water samples were analysed to differentiate human and animal faecal contamination of the New River, Mexico/USA, by genotyping bacterial viruses detected in the samples. From 46 water samples collected from the New River, 372 plaques of male-specific coliphages were isolated and genotyped; 44% of the plaques were identified as F-RNA coliphages and further characterized into four groups. Group I was the most prevalent (56%), followed by group IV (25%), group III (10%) and group II (9%). Group III coliphages were only detected at the sampling site in the vicinity of the international boundary, indicating human faecal contamination. As the New River traverses through the US region, groups I and IV coliphages were predominantly identified, but no human-specific genotypes were detected. The study also found that water temperature influenced the prevalence of the relative proportions of F-RNA coliphages in the environmental water samples. The strategy used in this study appears to be a practical and reliable tool for monitoring and distinguishing between human and animal faecal contamination.

Legionella - A threat to groundwater: Pathogen transport in recharge basin.

This study elucidates the potential risk posed by Legionella during aquifer recharge practices. Experiments were conducted using pilot-scale column simulating infiltration of bacterial surrogate and pathogen, E. coli and Legionella pneumophila, under central Arizona recharge basin conditions. A column was packed with a loamy sand media collected from a recharge basin and was fitted with six sampling ports at soil depths of 15, 30, 60, 92, 122cm and acclimated for a month with tertiary treated wastewater. Transport of Legionella appeared to be delayed compared to E. coli. The breakthrough of E. coli and Legionella at 122cm depth occurred at 3 and 24h, respectively. Slow transport of Legionella is consistent with its pleomorphic nature and variation in size and shape under low nutrient conditions. Legionella persisted for a longer time in the column, but at lower concentrations. Given the novel results of this study, the transport of Legionella into groundwater aquifers can occur through engineering recharge basin conditions creating a potential public health risk.

Physisorption and chemisorption of T4 bacteriophages on amino functionalized silica particles.

Bacteriophages, or phages, are receiving increasing interest as recognition tools for the design of bioactive surfaces. However, to maintain the activity of surface-bound phages, the immobilization strategy must provide the right orientation and not compromise the phages' integrity. The objectives of this study were to characterize the phage sorption capacity and the immobilized phage activity for aminated silica particles functionalized with T4 phages. Two functionalization strategies were compared; physisorption, based on electrostatic adhesion, and chemisorption, where the phage and the particle are coupled using a carbodiimide cross-linker. We report that chemisorption, at maximum adsorption conditions on 1 µm particles, yielded 16 functional phages per particle, which is 2.5 times more than by the physisorption method. Particle diameter is shown to have an important impact on phage attachment and 1.8 µm particles were found to have ∼4 times more phages per surface area than 0.5 µm particles. Higher surface coverage is attributed to the lower steric hindrance on bigger particles. These findings provide important guidelines for the design of phage-functionalized particles for environmental, biomedical, or sensing applications.

A Strategy to Establish a Quality Assurance/Quality Control Plan for the Application of Biosensors for the Detection of E. coli in Water.

Rapid bacterial detection using biosensors is a novel approach for microbiological testing applications. Validation of such methods is an obstacle in the adoption of new bio-sensing technologies for water testing. Therefore, establishing a quality assurance and quality control (QA/QC) plan is essential to demonstrate accuracy and reliability of the biosensor method for the detection of E. coli in drinking water samples. In this study, different reagents and assay conditions including temperatures, holding time, E. coli strains and concentrations, dissolving agents, salinity and pH effects, quality of substrates of various suppliers of 4-methylumbelliferyl glucuronide (MUG), and environmental water samples were included in the QA/QC plan and used in the assay optimization and documentation. Furthermore, the procedural QA/QC for the monitoring of drinking water samples was established to validate the performance of the biosensor platform for the detection of E. coli using a culture-based standard technique. Implementing the developed QA/QC plan, the same level of precision and accuracy was achieved using both the standard and the biosensor methods. The established procedural QA/QC for the biosensor will provide a reliable tool for a near real-time monitoring of E. coli in drinking water samples to both industry and regulatory authorities.

Aerobiology of the built environment: Synergy between Legionella and fungi.

BACKGROUND: The modern built environment (BE) design creates unique ecological niches ideal for the survival and mutual interaction of microbial communities. This investigation focused on the synergistic relations between Legionella and the fungal species commonly found in BEs and the impact of these synergistic relationships on the survival and transmission of Legionella. METHODS: A field study was conducted to identify the types and concentrations of fungi in BEs. The fungal isolates purified from BEs were cocultured with Legionella to study their synergistic association. Cocultured Legionella cells were aerosolized in an air-tight chamber to evaluate the efficacy of ultraviolet (UV) to inactivate these cells. RESULTS: Aspergillus, Alternaria, and Cladosporium were the most common fungi detected in samples that tested positive for Legionella. After coculturing, Legionella cells were detected inside fungal hyphae. The microscopic observations of Legionella internalization in fungal hyphae were confirmed by molecular analyses. UV disinfection of the aerosolized Legionella cells that were cocultured with fungi indicated that fungal spores and propagules act as a shield against UV radiation. The shield effect of fungal spores on Legionella cells was quantified at >2.5 log10. CONCLUSIONS: This study provides the first evidence, to our knowledge, of Legionella cell presence inside fungi detected in an indoor environment. This symbiotic relationship with fungi results in longer survival of Legionella under ambient conditions and provides protection against UV rays.

A biosensor platform for rapid detection of E. coli in drinking water.

There remains a need for rapid, specific and sensitive assays for the detection of bacterial indicators for water quality monitoring. In this study, a strategy for rapid detection of Escherichia coli in drinking water has been developed. This strategy is based on the use of the substrate 4-methylumbelliferyl-ß-d-glucuronide (MUG), which is hydrolyzed rapidly by the action of E. coli ß-d-glucuronidase (GUD) enzyme to yield a fluorogenic 4-methylumbelliferone (4-MU) product that can be quantified and related to the number of E. coli cells present in water samples. In this study, the detection time required for the biosensor response ranged between 20 and 120 min, depending on the number of bacteria in the sample. This approach does not need extensive sample processing with a rapid detection capability. The specificity of the MUG substrate was examined in both, pure cultures of non-target bacterial genera such as Klebsiella, Salmonella, Enterobacter and Bacillus. Non-target substrates that included 4-methylumbelliferyl-ß-d-galactopyranoside (MUGal) and l-leucine ß-naphthylamide aminopeptidase (LLß-N) were also investigated to identify nonspecific patterns of enzymatic activities in E. coli. GUD activity was found to be specific for E. coli and no further enzymatic activity was detected by other species. In addition, fluorescence assays were performed for the detection of E. coli to generate standard curves; and the sensitivity of the GUD enzymatic response was measured and repeatedly determined to be less than 10 E. coli cells in a reaction vial. The applicability of the method was tested by performing multiple fluorescence assays under pure and mixed bacterial flora in environmental samples. The results of this study showed that the fluorescence signals generated in samples using specific substrate molecules can be utilized to develop a bio-sensing platform for the detection of E. coli in drinking water. Furthermore, this system can be applied independently or in conjunction with other methods as a part of an array of biochemical assays in order to reliably detect E. coli in water.

A tool box strategy using Bacteroides genetic markers to differentiate human from non-human sources of fecal contamination in natural water.

Bacteroides genetic markers have been widely used to identify fecal pollution of water originating from human and animal sources. Many of the assays currently used for detecting human-specific Bacteroides produce false positive results. The focus of this study was to develop a microbial source tracking (MST) tool box strategy for differentiating Bacteroides from human and animal sources. Bacteroides 16S rRNA gene sequences from fish and selected animals were aligned against human fecal Bacteroides isolates to compare and characterize the variable regions within the 16S rRNA gene sequence. Conserved sequences between 4 variable regions were deleted and the truncated sequences were combined to develop a hyper-variable genomic segment (HVGS). The cladogram created from truncated sequences show a clear separation of Bacteroides from human feces and those from animal sources. The proposed strategy was field tested by collecting water samples from central Arizona source waters and three different recreational ponds. PCR using HF134 and HF183 primer sets was performed and sequences from positive reactions were aligned against human Bacteroides sequences to identify the source of contamination. Based on PCR results, the source of fecal contamination was presumptively identified as either human or from another source. For samples testing positive using the HF183 primer set (8/13), fecal contamination was presumed to be from human sources, but to confirm the results, PCR products were sequenced and aligned against the four variable regions and then incorporated within the truncated cladogram. As expected, the sequences from water samples with human fecal contamination grouped in a separate clade. A variability matrix, developed after exclusion of conserved sequences among the four regions, was utilized to establish discrete groupings for sequences within the truncated cladogram, generally differentiating Bacteroides isolates from varying host animals, but most importantly, separating Bacteroides from human feces from Bacteroides from other animals. The proposed strategy offers a new tool box method for MST and a step-wise methodology essential for identifying human sources of fecal pollution.

An assessment of water quality and microbial risk in Rio Grande Basin in the United States-Mexican border region.

Increased reliance of urban populations on Rio Grande water has necessitated an expanded microbial surveillance of the river to help identify and evaluate sources of human pathogens, which could pose a public health risk. The objectives of this study were to investigate microbial and chemical water quality in Rio Grande water and to perform risk assessment analyses for Cryptosporidium. No oocysts in any of the ten-litre samples were detected. However, the limit of detection in the water samples ranged between 20 and 200 oocysts/100 L. The limits of detection obtained in this study would result in one to two orders of magnitude higher risk of infection for Cryptosporidium than the U.S.EPA annual acceptable risk level of 10(-4). The bacterial data showed the significance of animal farming and raw sewage as sources of fecal pollution. Male specific and somatic coliphages were detected in 52% (11/21) and 62% (24/39) of the samples, respectively. Somatic coliphages were greater by one order of magnitude, and were better correlated with total (r2 = 0.6801; p < or = 0.05) and fecal coliform bacteria (r2 = 0.7366; p < or = 0.05) than male specific coliphages. The dissolved organic carbon (DOC) and specific ultraviolet absorbance (SUVA) values ranged 2.58-5.59mg/L and 1.23-2.29 m(-1) (mg/I)(-1), respectively. Low SUVA values of raw water condition make it difficult to remove DOC during physical and chemical treatment processes. The microbial and chemical data provided from this study can help drinking water utilities to maintain balance between greater microbial inactivation and reduced disinfection by-products (DBPs) formation.