Microbiological Water Quality Research Articles

Addressing underestimation of waterborne disease risks due to fecal indicator bacteria bound in aggregates.

This study aims to identify and address significant limitations in current culture-based regulatory methods used for monitoring microbiological water quality. Specifically, these methods' inability to distinguish between planktonic forms and aggregates containing higher bacterial loads and associated pathogens may lead to a severe underestimation of exposure risks, with critical public health implications. We employed a novel methodology combining size fractionation with ALERT, an automated rapid method for comprehensive quantification of culturable fecal indicator bacteria (FIB). Our findings reveal a substantial and widespread presence of aggregate-bound indicator bacteria across various water matrices and geographical locations. Comprehensive bacterial counts consistently exceeded those obtained by traditional methods by significant multiples, such as an average of 3.4×at the Seine River 2024 Olympic venue, and occasionally up to 100×in irrigation canals and wastewater plant effluent. These results, supported by microscopic and molecular analyses, underscore a systematic bias in global water safety regulatory frameworks. Our research demonstrates the inadequacy of traditional culture-based techniques in assessing microbiological risks posed by aggregate-bound FIB and associated pathogens, particularly in water matrices affected by FIB-rich fecal particles from recent sewer overflows or sediment, which can carry higher infectious risks. Incorporating comprehensive FIB analysis techniques, including molecular methods and rapid culture-based approaches as shown in this study, offers a promising and effective solution to these risk assessment limitations.

In-vitro and in-vivo assessment of the bactericidal potential of peracetic acid and hydrogen peroxide disinfectants against A. hydrophila infection in Nile tilapia and their effect on water quality indices and fish stress biomarkers

This study aimed to assess the in vitro and in vivo disinfectant potential of peracetic acid (PAA) (1 mg/L) and hydrogen peroxide (H2O2) (20 mg/L) on the physicochemical and microbiological water quality parameters of fish aquaria, the microbial density of Nile tilapia muscular tissue, fish hepatic cortisol levels, and antioxidant biomarkers. In vitro, PAA and H2O2 reduced A. hydrophila colony viability by 5 log units after 30 and 5 min of contact time, respectively. PAA and H2O2 were added to aquaria water twice a week for the three-week experiment. Increased fish escape reflexes were observed only in the PAA group, which returned to normal within 10 min. No mortalities were reported in either the PAA or H2O2 groups. An in vivo experimental challenge with a pathogenic strain of A. hydrophila revealed a 20% reduction in mortality in the PAA group, with no mortalities in the H2O2 group. Cortisol levels and antioxidant markers were measured to assess the impact of PAA and H2O2 on fish health. Cortisol levels in the PAA and H2O2 groups were significantly higher than in the control group after disinfectant exposure, but they progressively returned to normal. A significant reduction in superoxide dismutase (SOD) and catalase (CAT) activity, along with considerably higher glutathione peroxidase (GPx) and malondialdehyde (MDA) enzymatic activity, was observed in the PAA and H2O2 groups compared to the control group. A substantial increase in total antioxidant capacity (TAC) was recorded in the PAA group. Physicochemical analyses revealed reduced pH and increased dissolved oxygen levels in the PAA and H2O2 groups. Microbiological analyses showed a significant reduction in bacterial density in water by 64% and 76% after 30 min of exposure to PAA and H2O2, respectively, with a non-significant increase in microbial count after bacterial challenge. Additionally, aerobic bacterial count, Aeromonas spp., and psychotropic bacterial count in fish muscle showed a significant reduction in the H2O2 group compared to the PAA and control groups before and after infection. The study concludes that regular application of PAA and H2O2 can temporarily reduce bacterial load in aquaria and fish muscle, regulate stress responses, and improve fish health by reducing A. hydrophila-induced infections and improving survival.

Multivariate statistical analysis as a tool for monitoring drinking water sources in an Atlantic Rainforest Conservation Unit.

Water quality monitoring is paramount in identifying and mitigating pollution sources, protecting aquatic ecosystems, and ensuring safe water for human and wildlife consumption. This study is aimed at evaluating the quality of drinking water sources in three communities located in a Sustainable Use Conservation Unit in the municipality of Mangaratiba, Rio de Janeiro, Brazil, employing a multivariate statistical analysis. A total of 161 water samples were collected from January to December 2022, encompassing 32 surface water and 129 tap water samples. Physicochemical parameters were determined in situ employing a Horiba U50 multiparameter probe. The samples were stored and transported at 4°C to the laboratory for microbiological analyses concerning total coliforms and Escherichia coli using a commercial enzymatic test. All samples contained coliforms, while E. coli were detected in 87% of the samples. The multivariate analysis indicated that the microbiological water quality in sampling region R2 was influenced by rainy periods and that, in general, the water quality within R3 was the most affected by the transport of solids to the water sources. The statistical methods applied herein aided in characterizing the study areas and detecting points of attention regarding physicochemical and microbiological parameters that significantly influence the water quality of each sampling point. Representative points for each study region were identified and may be employed for future monitoring and prevention actions.

Characterization and evaluation of physiochemical and microbiological water quality parameters in Palestinian schools: a case study from Central Hebron Directorate

Characterization and evaluation of physiochemical and microbiological water quality parameters in Palestinian schools: a case study from Central Hebron Directorate

The microbiological quality of bottled and tap water: Risks and regulations

The microbiological quality of bottled and tap water: Risks and regulations

Enhancing infection control in dialysis at a resource limited public healthcare institute: A cross-sectional study on microbiological quality assessment of dialysis water and dialysate

PurposeTo evaluate the microbiological quality of dialysis water and dialysate samples from hemodialysis units at a tertiary care government hospital and to assess the use of culture, endotoxin and periodicity of testing these assays to guide the actions of monitoring the quality of hemodialysis fluids, implement preventive and corrective actions, and improve the safety and outcomes of the dialysis process. MethodsA cross-sectional study was conducted at a 250-bedded super-specialty government hospital with a 24/7 hemodialysis unit equipped with 40 dialysis machines. Dialysis water and dialysate samples were collected monthly and analysed for microbial contamination and endotoxin levels as per AAMI guidelines. Bacterial cultures were done using Reasoner's Agar plates, and endotoxin analysis was performed using gel clot assay. Interpretation of results was based on predefined thresholds. ResultsAmong the 740 samples processed for microbial culture 19.6 % and 80.4% were unacceptable and acceptable respectively.Among the acceptable samples 10.5 % were at action level. At the end of 2 days of incubation, 15.2%dialysis water samples and 5.1%dialysate samples had unacceptable levels of bacterial colonies and at 5days additional 10.6 % dialysis water samples and 7.7%dialysate samples were unacceptable. 21.5 % of the samples tested for endotoxin had unacceptable levels. ConclusionsRegular monitoring of water quality in government healthcare hemodialysis units is crucial for quality of care, timely preventive and corrective actions for mitigating adverse outcomes. Processing cultures for 5–7 days is essential for detecting all contaminated specimens. While there might be a link between endotoxin levels and bacterial contamination, both endotoxin testing and bacterial culture independently are vital for evaluating water quality in dialysis settings. A comprehensive approach integrating various testing methods is necessary to uphold patient safety and enable necessary improvements.

Estimation of soil loss using RUSLE model and GIS tools: Case study in the Jucusbamba Micro-Watershed (Amazonas, NW Peru)

Human activities have intensified soil erosion globally, negatively impacting the physical, chemical, and microbiological quality of water and soil. This study estimated soil loss in the Jucusbamba Micro-Watershed (Amazonas, northwestern Peru) using the Revised Universal Soil Loss Equation (RUSLE) integrated with Geographic Information Systems (GIS) and remote sensing (RS) data. Meteorological data, soil maps, digital elevation models, and land cover and use maps were integrated into a GIS environment to predict the spatial distribution of erosion. The results showed five classes of soil loss severity: slight (93.34%), moderate (3.94%), high (1.82%), very high (0.61%), and severe (0.29%). Areas with high, very high, and severe erosion levels were mainly located in the middle and lower parts of the micro-watershed. The average annual soil loss was estimated at 23.24 t/ha/year. The information obtained is crucial for the formulation of soil management plans and programs to address erosion problems in the Jucusbamba River Micro-Watershed. Future research should focus on validating these models through field studies and implementing soil conservation practices based on these findings. Keywords: Amazonas, hydrology, RUSLE model, water erosion map, watershed.

Microbiological Quality of Coconut Water Sold in the Grande Vitória Region, Brazil, and Phenogenotypic Antimicrobial Resistance of Associated Enterobacteria.

This study aimed to evaluate the microbiological quality of coconut water sold from street carts equipped with cooling coils or refrigerated at bakeries in the Grande Vitória Region, Brazil. Additionally, it assessed the phenotypic and genotypic antimicrobial resistance profiles of isolated enterobacteria. The results indicated that coconut water sold at street carts had lower microbiological quality compared to refrigerated samples, as evidenced by significantly higher counts of mesophilic microorganisms. Using MALDI-TOF, the following opportunistic pathogens were identified: Citrobacter freundii, Enterobacter bugandensis, E. kobei, E. roggenkampii, Klebsiella pneumoniae, and Kluyvera ascorbata. Three isolates-E. bugandensis, K. pneumoniae, and K. ascorbata-were classified as multidrug-resistant (MDR). Widespread resistance to β-lactams and cephalosporins was detected, and some isolates were resistant to quinolones, nitrofurans, and phosphonic acids. The gene blaCTX-M-2 was detected in C. freundii, E. bugandensis, E. kobei, and K. ascorbata. However, genes blaNDM, blaKPC, blaCMY-1, and blaCMY-2 were not detected in any isolate. The findings underscore the need to enhance good manufacturing practices in this sector to control the spread of antimicrobial resistance (AMR). To our knowledge, this is the first study documenting the presence of potentially pathogenic enterobacteria in coconut water samples and their associated phenotypic and genotypic AMR profiles.

Efficiency of EMB Medium Combined with MALDI-TOF in Isolating and Identifying Coliform Lactose Fermenters and Non-Lactose Fermenters from Wastewater

In Côte d'Ivoire, the sewer network is largely underdeveloped, resulting in the absence or incompleteness of sanitation infrastructure in many urban and rural areas. This lack of infrastructure leads to untreated wastewater being frequently discharged into rivers and other sources of drinking water. The contamination of water sources by untreated wastewater spreads waterborne diseases, which particularly affect children and vulnerable populations. Coliforms, as key indicators of the microbiological quality of water, play a crucial role in assessing health risks. The presence and diversity of these coliforms can provide insights into the extent of water contamination and the potential health risks to the population. This study focuses on the diversity of lactose-fermenting and non-lactose-fermenting coliforms in the wastewater of Abidjan. The objective is to use MALDI-TOF mass spectrometry for the rapid and accurate identification of these coliforms, thereby providing a detailed understanding of the microbiological quality of wastewater. The study aims to identify the predominant coliform species present in the wastewater and assess their potential impact on public health. Out of 80 wastewater samples collected from various locations in Abidjan, a preponderance of lactose-fermenting coliforms was found. The most frequently identified species were Klebsiella pneumoniae and Escherichia coli. The results showed that these species were present in significantly higher numbers compared to non-lactose-fermenting coliforms. The use of MALDI-TOF mass spectrometry allowed for rapid and precise identification of the coliforms, facilitating a comprehensive analysis of the microbiological quality of the wastewater. These findings underscore the urgent need for improved wastewater management strategies in Abidjan and similar urban settings in Côte d'Ivoire. The high prevalence of lactose-fermenting coliforms, particularly Klebsiella pneumoniae and Escherichia coli, in untreated wastewater poses significant public health risks. Effective wastewater treatment and management are essential to protect public health, reduce the spread of waterborne diseases, and limit the development of antimicrobial resistance. Implementing such measures will require coordinated efforts from local authorities, public health officials, and the community to ensure safe and sustainable water practices.

Exploring the nexus between water quality and land use/land cover change in an urban watershed in Uruguay: a machine learning approach.

The expansion of urban areas contributes to the growth of impervious surfaces, leading to increased pollution and altering the configuration, composition, and context of land covers. This study employed machine learning methods (partial least square regressor and the Shapley Additive exPlanations) to explore the intricate relationships between urban expansion, land cover changes, and water quality in a watershed with a park and lake. To address this, we first evaluated the spatio-temporal variation of some physicochemical and microbiological water quality variables, generated yearly land cover maps of the basin adopting several machine learning classifiers, and computed the most suitable landscape metrics that better represent the land cover. The main results highlighted the importance of spatial arrangement and the size of the contributing watershed on water quality. Compact urban forms appeared to mitigate the impact on pollutants. This research provides valuable insights into the intricate relationship between landscape characteristics and water quality dynamics, informing targeted watershed management strategies aimed at mitigating pollution and ensuring the health and resilience of aquatic ecosystems.

Microbial Health Risks of Cryptosporidium parvum and Giardia lamblia in Tropical Coastal Water in Araromi, Nigeria.

Giardia and Cryptosporidium are enteric protozoa that can cause a variety of gastrointestinal diseases, especially in vulnerable people like children, the elderly, and those with impaired immune systems. In order to ascertain the microbiological quality of the recreational water from Araromi Beach in Ilaje Local Government Area, Ondo State, Nigeria. This risk assessment is of great significance to human health protection against waterborne diseases. The aim of this study was to determine the microbial quality of recreational water from Araromi Beach in Ilaje Local Government Area, Ondo State, Nigeria. Microscopic examination of Cryptosporidium and Giardia oocysts were done. Results revealed maximum occurrence of Cryptosporidium parvum (20 oocysts/100 mL) of water sample in the month of April and maximum occurrence of Giardia lamblia (300 cysts/100 mL) of water sample in the month of June. Additionally, according to Kolmogorov-Smirnov tests for normalcy Ho =0.05, Giardia lamblia and Cryptosporidium parvum were not regularly distributed in the water samples collected from the beach throughout the study period. The average likelihood of contracting Giardia lamblia and Cryptosporidium parvum infections after consuming 100 mL of beach water was 0.96 and 0.35, respectively. The risks of infection associated with Cryptosporidium parvum was lower than those associated with Giardia lamblia in water from the beach, but were both above the acceptable risk limit of 10-4. The results of this study indicate that Giardia and Cryptosporidium may represent serious health hazards to people who engage in aquatic activities. Adopting a comprehensive strategy that includes regular inspections, enhanced detection techniques, and the prevention of aquatic environment pollution may provide clean and safe recreational water for all, thereby safeguarding the public's health.

Long-term impact of basin-wide wastewater management on faecal pollution levels along the entire Danube River

The Danube River is, at 2857 km, the second longest river in Europe and the most international river in the world with 19 countries in its catchment. Along the entire river, faecal pollution levels are mainly influenced by point-source emissions from treated and untreated sewage of municipal origin under base-flow conditions. In the past 2 decades, large investments in wastewater collection and treatment infrastructure were made in the European Union (EU) Member States located in the Danube River Basin (DRB). Overall, the share of population equivalents with appropriately biologically treated wastewater (without disinfection) has increased from 69% to more than 85%. The proportion of tertiary treatment has risen from 46 to 73%. In contrast, no comparable improvements of wastewater infrastructure took place in non-EU Member States in the middle and lower DRB, where a substantial amount of untreated wastewater is still directly discharged into the Danube River. Faecal pollution levels along the whole Danube River and the confluence sites of the most important tributaries were monitored during four Danube River expeditions, the Joint Danube Surveys (JDS). During all four surveys, the longitudinal patterns of faecal pollution were highly consistent, with generally lower levels in the upper section and elevated levels and major hotspots in the middle and lower sections of the Danube River. From 2001 to 2019, a significant decrease in faecal pollution levels could be observed in all three sections with average reduction rates between 72 and 86%. Despite this general improvement in microbiological water quality, no such decreases were observed for the highly polluted stretch in Central Serbia. Further improvements in microbiological water quality can be expected for the next decades on the basis of further investments in wastewater infrastructure in the EU Member States, in the middle and lower DRB. In the upper DRB, and due to the high compliance level as regards collection and treatment, improvements can further be achieved by upgrading sewage treatment plants with quaternary treatment steps as well as by preventing combined sewer overflows. The accession of the Western Balkan countries to the EU would also significantly boost investments in wastewater infrastructure and water quality improvements in the middle section of the Danube. Continuing whole-river expeditions such as the Joint Danube Surveys is highly recommended to monitor the developments in water quality in the future.

Chemical and Microbiological Quality of Municipal Supply Water in Dhaka South Area, Bangladesh

This project aimed to find out the microbiological quality of municipal supply water in Dhaka South area and if the current regime of microbiological quality testing can determine the risk to public health from supply water satisfactorily. Water samples were collected from six different points of the water distribution network of Dhaka’s south locality, starting from the source (Shitalakhyariver, Narayanganj) to Jagannath University, Dhaka. The dominant taxonomic units were isolated using standard culture techniques, followed by biochemical identification, VITEK2 identification, and biofilm-forming potential of each isolate individually and co-cultured with other isolates. Presumptive identification of isolates from the Shitalakhya River revealed the presence of Citrobacter sp., Alcaligenes sp., and Pseudomonas putida. The sample from Saydabad Water Treatment Plant yielded Vibrio mimicus, Pseudomonas fluorescence, and Alcalimonas. The major aerobic bacteria in the water specimen from the community overhead tank included S aureus, Bacillus cereus, Micrococcus sp., Enterococcus sp., Lactococcus sp. Tap water revealed the presence of Escherichia coli, Lactococcus, Enterobacter, Shigella, Klebsiella, Pseudomonas, and Staphylococcus aureus, as well as anaerobic bacteria. Biochemical tests and VITEK2 yielded different results. Potential biofilm formers such as Klebsiella, E. coli, Enterococcus, Aerococcus, Enterobacter, and Cronobacter indicated quality deterioration potential inside the piped water supply system. Alteration in the major taxonomic units throughout the municipal water distribution network and the presence of opportunistic pathogens and biofilm-formers indicate the necessity for an updated water treatment, quality control, and in-line maintenance system.

Determination of Baseline Data of Physicochemical and Microbiological Quality of Surface Waters in Nsit Ibom Local Government Area of Akwa Ibom State, Nigeria

Determination of Baseline Data of Physicochemical and Microbiological Quality of Surface Waters in Nsit Ibom Local Government Area of Akwa Ibom State, Nigeria

Two-year Monitoring of Microbiological Water Quality in Small Water Supply Systems: Implications for Microbial Risk Management.

Small water supply systems (SWSSs) are often more vulnerable to waterborne disease outbreaks. In Japan, many SWSSs operate without regulation under the Waterworks Law, yet there is limited investigation into microbial contamination and the associated health risks. In this study, the microbiological water quality of four SWSSs that utilize mountain streams as water sources and do not install water treatment facilities were monitored for over 2 years. In investigated SWSSs, the mean heterotrophic plate counts were below 350 CFU/mL, and the total bacterial loads (16S rDNA concentration) ranged from 4.71 to 5.35 log10 copies/mL. The results also showed the consistent presence of fecal indicator bacteria (FIB), i.e., Escherichia coli and Clostridium perfringens, suggesting the potential of fecal pollution. E. coli was then utilized as an indicator to assess the health risk posed by E. coli O157:H7 and Campylobacter jejuni. The results indicated that the estimated mean annual risk of infection and disability-adjusted life years (DALYs) exceeded acceptable levels in all SWSSs for the two reference pathogens. To ensure microbial water safety, implementing appropriate water treatment facilities with an estimated mean required reduction of 5-6 log10 was necessary. This study highlighted the potential microbial contamination and health risk level in SWSSs that utilize mountain streams as water sources, even though the water sources were almost not affected by human activities. Furthermore, this study would also be helpful in supporting risk-based water management to ensure a safe water supply in SWSSs.

Microbiological Quality of Irrigation Water and Leafy Vegetables in Dar es Salaam, Tanzania

The quality of water used for the irrigation of leafy vegetables in urban settings is in doubt due to contamination associated with poor hygiene and water pollution. This study examined the microbiological quality of irrigation water and leafy vegetables at Chang’ombe in Dar es Salaam, Tanzania as well as the perceptions and level of awareness of nearby consumers. Water and leafy vegetable samples were analysed for faecal coliform (FC) using standard techniques. Perception and awareness of consumers were collected using a questionnaire survey. The results showed an average FC count of 406.1 ± 16.40 MPN/100 ml for the irrigation water. The sweet potato leaves and amaranth had FC counts of 11.40 ± 5.220 CFU/g and 17.60 ± 11.98 CFU/g respectively. The levels of FC in irrigation water and leafy vegetables were within the allowed limits by WHO and NAS-USA standards respectively but fall short of some stricter European standards for irrigation water. The household survey showed that consumers perceive irrigation water at Chang’ombe as polluted and may be one of the main sources of food contamination. They minimize associated health risks in various ways such as using clean storage, washing and cooking. It was concluded that the microbial quality of water used for irrigation of leafy vegetables at Chang’ombe poses no risk to public health, but based on tighter standards, improved public awareness of hygienic practices is crucial to address potential risks.

Safety of Tap Water in Terms of Changes in Physical, Chemical, and Biological Stability

Monitoring the quality of tap water in the distribution system and the ability to estimate the risk of losing its sanitary safety is an important aspect of managing the collective water supply system. During monitoring, the physical, chemical, and biological stability of water was assessed, which is the main determinant ensuring the appropriate quality of water for consumers. The physicochemical and microbiological quality of water was analyzed for two distribution systems (DSs), including the analysis of heavy metals (Zn, Fe, Mn, Cr, Ni, Cu, Cd, Pb). The tests carried out showed that in both distribution systems, the water supplied to consumers met the guidelines for water intended for human consumption. It can be considered that the risk of uncontrolled changes in water quality in DSs with an average water production of <10,000 m3/d and the length of water pipelines < 150 km is very low. The water introduced into the system differed in the place of water intake and water purification technology, which influenced the final water quality. In DS(II), higher values were recorded for hardness, conductivity, calcium, alkalinity, nitrates, and DOC. It was found that the content of heavy metals during water transport to the consumer increased in the case of DS(I) for Zn, Ni, Cu, Cd, and Pb, and in the case of DS(II) for Fe, Mn, Ni, Cu, Cd, and Pb. The observed differences resulted from the different quality of the intake water as well as from different materials used to build internal installations and their age and technical condition. The analyzed tap water was characterized by physical and chemical stability. However, the water did not meet the guidelines for water biostability due to the increased content of biogenic substances.

Influence of combined abiotic/biotic factors on decay of P. aeruginosa and E. coli in Rhine River water

Understanding the dynamic change in abundance of both fecal and opportunistic waterborne pathogens in urban surface water under different abiotic and biotic factors helps the prediction of microbiological water quality and protection of public health during recreational activities, such as swimming. However, a comprehensive understanding of the interaction among various factors on pathogen behavior in surface water is missing. In this study, the effect of salinity, light, and temperature and the presence of indigenous microbiota, on the decay/persistence of Escherichia coli and Pseudomonas aeruginosa in Rhine River water were tested during 7 days of incubation with varying salinity (0.4, 5.4, 9.4, and 15.4 ppt), with light under a light/dark regime (light/dark) and without light (dark), temperature (3, 12, and 20 °C), and presence/absence of indigenous microbiota. The results demonstrated that light, indigenous microbiota, and temperature significantly impacted the decay of E. coli. Moreover, a significant (p<0.01) four-factor interactive impact of these four environmental conditions on E. coli decay was observed. However, for P. aeruginosa, temperature and indigenous microbiota were two determinate factors on the decay or growth. A significant three-factor interactive impact between indigenous microbiota, temperature, and salinity (p<0.01); indigenous microbiota, light, and temperature (p<0.01); and light, temperature, and salinity (p<0.05) on the decay of P. aeruginosa was found. Due to these interactive effects, caution should be taken when predicting decay/persistence of E. coli and P. aeruginosa in surface water based on a single environmental condition. In addition, the different response of E. coli and P. aeruginosa to the environmental conditions highlights that E. coli monitoring alone underestimates health risks of surface water by non-fecal opportunistic pathogens, such as P. aeruginosa.Key pointsAbiotic and biotic factors interactively affect decay of E. coli and P. aeruginosaE.coli and P.aeruginosa behave significantly different under the given conditionsOnly E. coli as an indicator underestimates the microbiological water quality

Long-term trial of a community-scale decentralized point-of-use drinking water treatment system

Two billion people lack access to safely managed drinking water services, many of these are in low/middle income countries where centralised systems are impractical. Decentralised point-of-use drinking water treatment systems offer alternative solutions in remote or resource constrained settings. The main aim of this study was to assess the long-term (3 year) operation and performance of a point-of-use drinking water treatment system (POU-DWTS). A biologically contaminated urban drainage pond was used as a water source and the quality of the produced drinking water was assessed over two independent trials. The decentralised POU-DWTS combined ultrafiltration membranes with disinfection from electrochemically generated hypochlorous acid (HOCl). The operational parameters, such as flow rate, free available chlorine and transmembrane pressure, were monitored in real-time and recorded via a remote monitoring system. Water quality from the source and treated water was assessed over two trial periods within the 3-year operational trial: an 11-week period at the start and a 22-week trial at the end. All water samples were assessed for a range of basic, chemical, microbiological and metal water quality parameters. The results demonstrate that the decentralised POU-DWTS is capable of continuously producing high quality drinking water when HOCl is continuously used to dose water prior to entering the ultrafiltration [UF] membranes. Over the 3-year operational study, the continuous dosing of HOCl pre-UF membranes resulted in stable permeability, indicating no occurrences of irreversible biofouling within the UF membranes and that good membrane ‘health’ was maintained throughout. As such, there was no need to replace the UF membranes nor undertake acid/alkaline chemical cleans at any point throughput the three-year study. The POU-DWTS continuously produced high quality drinking water, resulting in 6453 m3 of drinking water produced over the trial period, that met international water quality standards, at a community scale within the location studied.

Microbiological quality of irrigation water on highly diverse fresh produce smallholder farms: elucidating environmental routes of contamination.

To evaluate the microbiological safety, potential multidrug-resistant bacterial presence and genetic relatedness (DNA fingerprints) of Escherichia coli isolated from the water-soil-plant nexus on highly diverse fresh produce smallholder farms. Irrigation water (n=44), soil (n=85), and fresh produce (n=95) samples from six smallholder farms with different production systems were analysed for hygiene indicator bacterial counts and the presence of shigatoxigenic E. coli and Salmonella spp. using standard microbiological methods. Identities of isolates were confirmed using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), and the genetic relatedness of the E. coli isolates determined using enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) analysis. Irrigation water E. coli levels ranged between 0 and 3.45 log MPN/100 ml-1 with five farms having acceptable levels according to the World Health Organization limit (3 log MPN/100 ml-1). Fresh produce samples on four farms (n=65) harboured E. coli at low levels (<1 log CFU/g-1) except for one sample from kale, spring onion, green pepper, onion, and two tomato samples, which exceeded international acceptable limits (100 CFU/g-1). Only one baby carrot fresh produce sample tested positive for Salmonella spp. Of the 224 samples, E. coli isolates were identified in 40% (n=90) of all water, soil, and fresh produce types after enrichment. Additionally, the DNA fingerprints of E. coli isolates from the water-soil-plant nexus of each respective farm clustered together at high similarity values (>90%), with all phenotypically characterized as multidrug-resistant. The clustering of E. coli isolated throughout the water-soil-plant nexus, implicated irrigation water in fresh produce contamination. Highlighting the importance of complying with irrigation water microbiological quality guidelines to limit the spread of potential foodborne pathogens throughout the fresh produce supply chain.