Tap water microbiome shifts in secondary water supply for high-rise buildings.

In high-rise buildings, secondary water supply systems (SWSSs) are pivotal yet provide a conducive milieu for microbial proliferation due to intermittent flow, low disinfectant residual, and high specific pipe-surface area, raising concerns about tap water quality deterioration. Despite their ubiquity, a comprehensive understanding of bacterial community dynamics within SWSSs remains elusive. Here we show how intrinsic SWSS variables critically shape the tap water microbiome at distal ends. In an office setting, distinct from residential complexes, the diversity in piping materials instigates a noticeable bacterial community shift, exemplified by a transition from α-Proteobacteria to γ-Proteobacteria dominance, alongside an upsurge in bacterial diversity and microbial propagation potential. Extended water retention within SWSSs invariably escalates microbial regrowth propensities and modulates bacterial consortia, yet secondary disinfection emerges as a robust strategy for preserving water quality integrity. Additionally, the regularity of water usage modulates proximal flow dynamics, thereby influencing tap water's microbial landscape. Insights garnered from this investigation lay the groundwork for devising effective interventions aimed at safeguarding microbiological standards at the consumer's endpoint.

A comprehensive dataset for the evaluation of a horizontal tubular flocculator implemented for drinking water treatment.

This article presents a set of data obtained during the evaluation of a horizontal flow tubular flocculator for the provision of drinking water in developing communities. The HFTF is presented as an alternative technology to replace conventional flocculators, allowing high efficiency in the subsequent sedimentation and filtration processes. For obtaining the data, experimental tests were carried out using lengths of 68.4 m and 97.6 m for the HFTF, these lengths were combined with flow rates of 0.25, 0.5, 0.75, 1.0 and 2.0 L/s, as well as raw water turbidities of 10, 20, 50, 100 and 200 NTU. The data set generated from measurements and observations made during experimental field tests is detailed. The resulting data set covers the main parameters that determine the quality of drinking water, such as turbidity and colour, as well as flocculation efficiency data. The data from the experimental system were compared with a conventional treatment plant that has a baffle flocculator. Likewise, data on the retention time and velocity gradient are presented that allowed the hydraulic characteristics of the HFTF are evaluated. This data set has significant potential for reuse in future research and development related to water treatment technologies in developing community settings. Detailed data has been collected on various operating conditions of the HFTF, such as different lengths, water flow rates and turbidity levels, as well as measurements of key parameters such as turbidity, colour, flocculation efficiency, retention time and velocity gradient, these Data could be used in future research and development related to water treatment technologies. Furthermore, a comparison of data from the experimental system with a conventional treatment plant provides useful insight into the relative performance of different water treatment technologies, which could be of interest to researchers, system designers and public policymakers in the field of drinking water supply in developing communities.

Water scarcity in the Kingdom of Saudi Arabia.

Saudi Arabia (SA) is one of the world's arid, most water-scarce nations without permanent water resources. The purpose of this article is to provide a comprehensive overview of Saudi Arabia's water resources availability and reliability in terms of water supply, demand, and the major challenges that water faces. Saudi has an annual water supply of roughly 89.5 m3 per person as consumption is rising in parallel with the country's rapid population growth and development. SA produces the most desalinated seawater in the world, accounting for 22% of worldwide consumption. Due to changes in agricultural demand, Saudi Arabia's overall water needs in 2020 were 15.98 BCM. Apart from agricultural use, the food industry utilizes up to 80% of freshwater supplies, with only around 20% of rain recharging the aquifer, meaning that the region will still be water-stressed by 2025. In addition to wastewater reuse, water expenses should be split between private investors and the government, and water losses in cities should be collected and recycled. Water development projects must also be safeguarded and have long-term viability for the community's future and well-being. Despite previous conservation efforts (public awareness campaigns, television and other public media messages, drip irrigation, and so on), more work is required, including improving water resource infrastructure, implementing environmental use of friendly technologies, and increasing economic feasibility, social acceptability, and management in light of the Sustainable Development Goals (SDG).

A novel robust evaluation approach to improve systematic behavior of failure safety in water supply system under various ellipsoid uncertainties.

This study proposes a novel robust optimization approach for an integrated water supply system, wherein the decision-makers attempt to improve failure safety of system under various uncertainty strategies. To cope with uncertainty, the ellipsoid uncertainty set is assumed to evaluate the best feasible solution in the direction of water supply under various strategies. We assessed the case of Hamoun watershed, a water-stressed watershed in southeastern of Iran, to evaluate the developed robust optimization model. In the following, the comparative feasibility under uncertainty levels is conducted to analyze the impacts of simulation strategies on the status of robust model. Based on the final results, the reliability of the model's objective functions experienced an increasing trend ( 58.3 % ), and the objective function values under the uncertainty strategies is greatly improved. The findings of the analysis show that the robust strategies in response to the failure safety achieve outstanding optimal objectives under uncertainty.

Variation of total alpha and beta activities and Rn-222 concentrations in the water supply system of an Italian volcanic region: How safe is tap water for human consumption?

Total alpha and beta activities and Rn-222 concentrations were determined in water from different sections of seven aqueducts belonging to the water supply system of Campania region (Italy), known worldwide for its volcanism. Statistical analysis was performed on data to account for their variability across the aqueduct sections, and results were discussed considering the geology of reservoirs, the potential mixing processes occurring along the pipe network, the building/constituting materials of the aqueduct sections, and the integrity of the infrastructure. Guidelines proposed by Italian and international regulation entities were considered to determine if total alpha and beta activities and Rn-222 concentrations found at the taps of the different aqueducts should be considered detrimental to public health. Based on a deterministic and a stochastic approach, a health risk assessment was also tested for Rn-222, assuming direct ingestion and showering as potential exposure pathways. Results showed that applying guidelines returned an absence of hazard, whereas risk assessment returned a high probability of exposure to unacceptable Rn-222 doses for some aqueducts. Beyond the usefulness of obtained results to plan actions to improve the safety of drinking water in Campania, our outcomes represent a warning for bodies dealing with public health at any level: the use of guidelines can bring an underestimation of the risks exerted by the exposure to Rn-222 on human health. Further, using a probabilistic approach in risk assessment accounting for uncertainty can favor risk forecasts based on more "realistic" scenarios.

Risk factors for Cryptosporidium contamination in Minnesota public supply wells.

In a recent monitoring study of Minnesota's public supply wells, Cryptosporidium was commonly detected with 40% of the wells having at least one detection. Risk factors for Cryptosporidium occurrence in drinking water supply wells, beyond surface water influence, remain poorly understood. To address this gap, physical and chemical factors were assessed as potential predictors of Cryptosporidium occurrence in 135 public supply wells in Minnesota. Univariable analysis, regression techniques, and classification trees were used to analyze the data. Many variables were identified as significant risk factors in univariable analysis and several remained significant throughout the succeeding analysis techniques. These factors fell into general categories of well use and construction, aquifer characteristics, and connectedness to the land surface, well capture zones, and land use therein, existence of potential contaminant sources within 200-feet of the well, and variability in the chemical and isotopic parameters measured during the study. These risk categories, and the specific variables and threshold values we have identified, can help guide future research on factors influencing Cryptosporidium contamination of wells and can be used by environmental health programs to develop risk-based sampling plans and design interventions that reduce associated health risks.

Tracking the changes of dissolved organic matter throughout the city water supply system with optical indices.

Dissolved organic matter (DOM) is important in determining the drinking water treatment and the supplied water quality. However, a comprehensive DOM study for the whole water supply system is lacking and the potential effects of secondary water supply are largely unknown. This was studied using dissolved organic carbon (DOC), absorption spectroscopy, and fluorescence excitation-emission matrices-parallel factor analysis (EEM-PARAFAC). Four fluorescent components were identified, including humic-like C1-C2, tryptophan-like C3, and tyrosine-like C4. In the drinking water treatment plants, the advanced treatment using ozone and biological activated carbon (O3-BAC) was more effective in removing DOC than the conventional process, with the removals of C1 and C3 improved by 17.7%-25.1% and 19.2%-27.0%. The absorption coefficient and C1-C4 correlated significantly with DOC in water treatments, suggesting that absorption and fluorescence could effectively track the changes in bulk DOM. DOM generally remained stable in each drinking water distribution system, suggesting the importance of the treated water quality in determining that of the corresponding network. The optical indices changed notably between distribution networks of different treatment plants, which enabled the identification of changing water sources. A comparison of DOM in the direct and secondary water supplies suggested limited impacts of secondary water supply, although the changes in organic carbon and absorption indices were detected in some locations. These results have implications for better understanding the changes of DOM in the whole water supply system to help ensure the supplied water quality.

Water Supply Interruptions Are Associated with More Frequent Stressful Behaviors and Emotions but Mitigated by Predictability: A Multisite Study.

Water supply interruptions contribute to household water insecurity. Unpredictable interruptions may particularly exacerbate water insecurity, as uncertainty limits households' ability to optimize water collection and storage or to modify other coping behaviors. This study used regression models of survey data from 2873 households across 10 sites in 9 middle-income countries to assess whether water supply interruptions and the predictability of interruptions were related to composite indicators of stressful behaviors and emotional distress. More frequent water service interruptions were associated with more frequent emotional distress (ß = 0.49, SE = 0.05, P < 0.001) and stressful behaviors (ß = 0.39, SE = 0.06, P < 0.001). Among households that experienced interruptions, predictability mitigated these respective relationships by approximately 25 and 50%. Where the provision of continuous water supplies is challenged by climate change, population growth, and poor management, water service providers may be able to mitigate some psychosocial consequences of intermittency through scheduled intermittency and communication about water supply interruptions. Service providers unable to supply continuous water should optimize intermittent water delivery to reduce negative impacts on users, and global monitoring regimes should account for intermittency and predictability in post-2030 water service metrics to better reflect household water insecurity experiences.

Interactive Effects of Microbial Fertilizer and Soil Salinity on the Hydraulic Properties of Salt-Affected Soil.

Significant research has been conducted on the effects of fertilizers or agents on the sustainable development of agriculture in salinization areas. By contrast, limited consideration has been given to the interactive effects of microbial fertilizer (MF) and salinity on hydraulic properties in secondary salinization soil (SS) and coastal saline soil (CS). An incubation experiment was conducted to investigate the effects of saline soil types, salinity levels (non-saline, low-salinity, and high-salinity soils), and MF amounts (32.89 g kg-1 and 0 g kg-1) on soil hydraulic properties. Applied MF improved soil water holding capacity in each saline soil compared with that in CK, and SS was higher than CS. Applied MF increased saturated moisture, field capacity, capillary fracture moisture, the wilting coefficient, and the hygroscopic coefficient by 0.02-18.91% in SS, while it was increased by 11.62-181.88% in CS. It increased soil water supply capacity in SS (except for high-salinity soil) and CS by 0.02-14.53% and 0.04-2.34%, respectively, compared with that in CK. Soil available, readily available, and unavailable water were positively correlated with MF, while soil gravity and readily available and unavailable water were positively correlated with salinity in SS. Therefore, a potential fertilization program with MF should be developed to increase hydraulic properties or mitigate the adverse effects of salinity on plants in similar SS or CS areas.

Microplastics contamination in water supply system and treatment processes.

Due to global demand, millions of tons of plastics have been widely consumed, resulting in the widespread entry of vast amounts of microplastic particles into the environment. The presence of microplastics (MPs) in water supplies, including bottled water, has undergone systematic review, assessing the potential impacts of MPs on humans through exposure assessment. The main challenges associated with current technologies lie in their ability to effectively treat and completely remove MPs from drinking and supply water. While the risks posed by MPs upon entering the human body have not yet been fully revealed, there is a predicted certainty of negative impacts. This review encompasses a range of current technologies, spanning from basic to advanced treatments and varying in scale. However, given the frequent detection of MPs in drinking and bottled water, it becomes imperative to implement comprehensive management strategies to address this issue effectively. Consequently, integrating current technologies with management options such as life-cycle assessment, circular economy principles, and machine learning is crucial to eliminating this pervasive problem.

Digital Twin of a Water Supply System Using the Asset Administration Shell.

The concept of digital twins is one of the fundamental pillars of Industry 4.0. Digital twin allows the realization of a virtual model of a real system, enhancing the relevant performance (e.g., in terms of production rate, risk prevention, energy saving, and maintenance operation). Current literature presents many contributions pointing out the advantages that may be achieved by the definition of a digital twin of a water supply system. The Reference Architecture Model for Industry 4.0 introduces the concept of the Asset Administration Shell for the digital representation of components within the Industry 4.0 ecosystem. Several proposals are currently available in the literature considering the Asset Administration Shell for the realization of a digital twin of real systems. To the best of the authors' knowledge, at the moment, the adoption of Asset Administration Shell for the digital representation of a water supply system is not present in the current literature. For this reason, the aim of this paper is to present a methodological approach for developing a digital twin of a water supply system using the Asset Administration Shell metamodel. The paper will describe the approach proposed by the author and the relevant model based on Asset Administration Shell, pointing out that its implementation is freely available on the GitHub platform.

Water Safety Practices Along the Water Service Chain in Addis Ababa: A Cross-Sectional Study in a Cosmopolitan City.

This study investigated water safety practices and risk levels along Addis Ababa's water supply service chain. The data came from 23 random woredas, 384 random households, 115 microbiological water quality tests, and diagnostic inspections from source to point of use. Findings from this study indicate that the surface water sources (53%) and the water source catchments (62%) are characterized by very high-risk and high risk contamination levels respectively. Conversely, the water treatment process (5%) and temporary reservoir (20%) indicates a low risk level. Whereas the water distribution system (40%), water source boreholes (44%), and Household level (29%) water safety practices are identified as medium risk levels. The microbial analysis of the drinking water at the source and point of use indicated low (<11 CFU/100 ml) to high levels (>100 CFU/100 ml) of risk with significant levels of contamination at the household level. Moreover, the household-level water safety practice assessment revealed intermediate to very high levels of risks. The Chi2 test shows that water supply type is significantly associated with occupation(X2(12,384) = 23.44, P < .05) and education(X2(8,384) = 15.4, P < .05). Multinomial regression analysis also showed better occupation is associated with increased access to safe bottled water compared to safe piped water on premises. It can be concluded that the water safety practice encountered low to very high levels of risk of contamination at different components along the water supply service chain and the household level. This study suggests ways to improve Addis Ababa residents' health and well-being through water safety interventions. These include safeguarding water sources, supporting local safe water businesses, providing household water treatment, and handling options, and addressing the barriers and incentives for adopting safe water practices.

Water Supply via Pedicel Reduces Postharvest Pericarp Browning of Litchi (Litchi chinensis) Fruit.

Pericarp browning is the key factor for the extension of shelf life and the maintenance of the commercial value of harvested litchi fruit. Water loss is considered a leading factor of pericarp browning in litchi fruit. In this study, based on the distinct structure of litchi fruit, which is a special type of dry fruit with the aril as the edible part, the effects of water supply via pedicel (WSP) treatment on pericarp browning and the fruit quality of litchi were investigated. Compared with the packaging of the control fruit at 25 °C or 4 °C, the WSP treatment was found to significantly reduce pericarp browning and the decay of litchi fruit. The WSP-treated fruit had a higher L* value, total anthocyanin content, and pericarp water content, and the pericarp was thicker. The WSP treatment significantly suppressed the increase in the electrolyte leakage of the pericarp and maintained higher ascorbic acid (AA) contents in the aril. In addition, the WSP treatment was effective in reducing the activity and gene expression of browning-related genes Laccase (ADE/LAC) and Peroxidase (POD) during the storage period. In conclusion, the WSP treatment could be an effective method to delay pericarp browning and maintain the quality of harvested litchi fruit, and this further supports that litchi fruit has dry fruit characteristics.

Water Supply Planning in the Face of Drought and Ecosystem Flows: Examining the Impact of the Bay-Delta Plan on Bay Area Water Supply.

In California, recent Bay-Delta Plan legislation attempts to balance water supply and ecosystem protection by requiring 40% of the flow to remain in-stream in the Tuolumne River from February through June. Serious questions remain about what this means for the Bay Area water supply, especially during drought. Our work develops a new approach to analyze how in-stream flow policy coupled with climate change could impact regional water supply over the coming decades. Results show that the new in-stream flow demand would exceed urban water deliveries in a typical year. In wet years, water supply performance is minimally impacted, but in drought, the policy can lead to less water in storage, delayed reservoir recovery, and increased time at critically low storage. Storage impact exceeding 50 000 acre-feet (60 million m3) is anticipated with at least 18% frequency, demonstrating that, climate uncertainty notwithstanding, this impact must be planned for and managed to ensure a reliable future water supply.

Achieving zero fouling in the ultrafiltration for secondary water supply systems in the absence of residual chlorine.

Ultrafiltration (UF) technology is widely used in secondary water supply systems (SWSS) to provide high-quality drinking water. However, the challenge of severe membrane fouling, which leads to frequent cleaning requirements, makes UF maintenance intensive. In this study, we tried to validate the feasibility of achieving zero fouling without the need for cleaning in the UF for SWSS, i.e., the fouling resistance can be maintained for a very long time without any increase. We operated dead-end UF systems at different fluxes, both with and without residual chlorine, and monitored the formation of fouling layers during filtration. The results demonstrated the successful achievement of zero fouling under a flux of 10 L/(m2 h) in the absence of chlorine, evidenced by no increase in transmembrane pressure for three months. This zero-fouling phenomenon was attributed to the formation of a self-regulating biofouling layer. This biofouling layer could degrade the deposited foulants and featured a loose morphology, facilitated by microbial activities in the cake layer. Although residual chlorine reduced the fouling rate by half at a flux of 30 L/(m2 h), it hindered the achievement of zero fouling at the lower flux of 10 L/(m2 h), due to its inhibitory effect on microbial activity. Intermittent operation of UF was effective in achieving zero fouling at higher fluxes (e.g., 30 L/(m2 h)). This benefit was primarily ascribed to the biodegradation of accumulated foulants and the expansion of biofouling layer during the pause of the intermittent filtration, which prompted the formation of biofouling layers with loose structure and balanced composition. To the best of our knowledge, this study is the first attempt to achieve zero fouling in UF for SWSS, and the findings may offer valuable insights for the development of cleaning-free and low-maintenance membrane processes.

The contribution of decentralized water systems on water quality in Maniema province, DRC.

Decentralized water systems (DWS) distribute water in remote African areas. Throughout an intervention in Maniema, Congo, the influence of a DWS performing chlorination in the community's water quality was measured. Additionally, a socio-economic and WASH practices survey was conducted in the communities. Free residual chlorine (FRC) and microbiological contamination were measured; at the borehole, treatment site, distribution points, and households's water containers. In Big Five, water was collected from unimproved sources before DWS construction. Despite that, only 16,6% of households used efficient water treatment methods, resulting in 73% of water stored unsafe for consumption. After construction, household water quality drastically improved, regardless of FRC fluctuations; 93% of samples were classified as low health risk (safe). The renovation guaranteed continuous supply through electro-chlorinators in RVA, where chlorination was intermittent. Water from DWS with adequate chlorine levels prevented microbiological contamination in households for 12 hours. Although economically attractive, the system's sustainability will require future evaluation.

Review of strategies to reduce the contamination of the water environment by gadolinium-based contrast agents.

Gadolinium-based contrast agents (GBCA) are essential for diagnostic MRI examinations. GBCA are only used in small quantities on a per-patient basis; however, the acquisition of contrast-enhanced MRI examinations worldwide results in the use of many thousands of litres of GBCA per year. Data shows that these GBCA are present in sewage water, surface water, and drinking water in many regions of the world. Therefore, there is growing concern regarding the environmental impact of GBCA because of their ubiquitous presence in the aquatic environment. To address the problem of GBCA in the water system as a whole, collaboration is necessary between all stakeholders, including the producers of GBCA, medical professionals and importantly, the consumers of drinking water, i.e. the patients. This paper aims to make healthcare professionals aware of the opportunity to take the lead in making informed decisions about the use of GBCA and provides an overview of the different options for action.In this paper, we first provide a summary on the metabolism and clinical use of GBCA, then the environmental fate and observations of GBCA, followed by measures to reduce the use of GBCA. The environmental impact of GBCA can be reduced by (1) measures focusing on the application of GBCA by means of weight-based contrast volume reduction, GBCA with higher relaxivity per mmol of Gd, contrast-enhancing sequences, and post-processing; and (2) measures that reduce the waste of GBCA, including the use of bulk packaging and collecting residues of GBCA at the point of application.Critical relevance statement This review aims to make healthcare professionals aware of the environmental impact of GBCA and the opportunity for them to take the lead in making informed decisions about GBCA use and the different options to reduce its environmental burden.Key points• Gadolinium-based contrast agents are found in sources of drinking water and constitute an environmental risk.• Radiologists have a wide spectrum of options to reduce GBCA use without compromising diagnostic quality.• Radiology can become more sustainable by adopting such measures in clinical practice.

Response mechanism of soil leachate and disinfection by-product formation to extreme precipitation events under continuous drought scenario.

In this study, a rainfall simulation device was employed to investigate the response mechanism of soil leachate and disinfection by-products formation potential (DBPsFP) to extreme precipitation events. The results revealed that the aromaticity of dissolved organic matter (DOM) and the concentration of hydrophobic DOM containing aromatic carbon groups in leachate decreased with rising temperature. The humification degree of DOM decreased at 25 °C (99 mm/h), while the humification degree and protein-like level of DOM increased under high temperatures droughts (45 °C and 65 °C). Higher temperatures resulted in the leach of more microbial-derived humus and low molecular phenolic compounds from soil and broadened the range of molecular weight distribution. Increasing temperature increased DBPsFP and DBPs species and caused the precursors of haloacetic acids (HAAs) in leachate to become more hydrophobic, while the precursors of trihalomethanes (THMs) became more hydrophilic. Most importantly, the increased temperature attenuated the rainfall-mediated dilution of organic pollutant concentration, and temperature has a more significant effect than extreme rainfall in DOM abundance and the formation potential (or species) of DBPs. The results help to better understand the impact of climate change on the physicochemical processes of water quality.

An economic evaluation of strategies to ensure safer drinking water in the homes of families with young children in select United States locations.

Introduction: In the United States, safe, accessible drinking water is not equitable due to source water contamination, unreliable water treatment, or hazardous plumbing infrastructure. Drinking water free of lead, nitrates, and arsenic is vital for infant and young children's health. Methods: Researchers conducted a study combining single-case study review methods and economic evaluation for 6 US policies or programs. Researchers used case-study findings, activity-based costing, publicly available US population data, and existing literature to create 5-year cost projections (2020-2024) for strategies to address lead, nitrates, or arsenic in drinking water from private wells or community water systems for families with low incomes and young children aged 0-5y. Researchers estimated the number of households reached and the costs by activity and payer of implementing each policy or program using case-specific geographic location and eligibility criteria. Results: The total number of households reached varied from 295 to 135,000 depending on water source, population of focus, and geographic location. Focused strategies reached higher proportions of families with low incomes and young children. Community water system and state-wide strategies had the broadest reach. The total annual program cost per household that received information about their water quality ranged from $75 to $2,780. Of this cost, the portion paid by the household varied from $0.12 to $1,590, not including mitigation. Conclusions: These findings can inform local decisions about policies and programs in communities seeking to increase awareness and access to safer drinking water, particularly in homes of families with low incomes and young children.

Quantitative health risk assessment of microbial hazards from water sources for community and self-supply drinking water systems.

In low and medium income countries (LMIC) drinking water sources (wells and boreholes) often contain a high number of pathogenic microorganisms, that can pose significant human and environmental health risks. In this study, a quantitative microbial risk assessment approach based on existing literature was conducted to evaluate and compare the quantitative health risks associated with different age groups using various drinking water supply systems. Results showed that both community-supply and self-supply modes exhibit similar levels of risk. However, the self-supply water source consistently showed higher risks compared to the community-supply one. Borehole water was found to be a more suitable option than well water, consistently showing between 5 and 8 lower health risks for E. coli and fecal coliform levels, respectively. The sensitivity analysis further showed the importance of prioritizing the reduction of E. coli concentration in well water and fecal coliform concentration in borehole water. This study offers a fresh perception on quantifying the impact of exposure concentration and age groups, shedding light on how they affect environmental health risks. These findings provide valuable insights for stakeholders involved in the management and protection of water sources.