This study explores the associations of drinking rainwater with mineral intake and cardiometabolic health in the Bangladeshi population. We pooled 10030 person-visit data on drinking water sources, blood pressure (BP) and 24-h urine minerals. Fasting blood glucose (FBG) was measured in 3724 person-visits, and lipids in 1118 person-visits. We measured concentrations of sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) in 253 rainwater, 935 groundwater and 130 pond water samples. We used multilevel linear or gamma regression models with participant-, household- and community-level random intercepts to estimate the associations of rainwater consumption with urine minerals and cardiometabolic biomarkers. Rainwater samples had the lowest concentrations of Na, K, Ca and Mg. Rainwater drinkers had lower urine minerals than coastal groundwater drinkers: -13.42 (95% CI: -18.27, -8.57) mmol Na/24 h, -2.00 (95% CI: -3.16, -0.85) mmol K/24 h and -0.57 (95% CI: -1.02, -0.16) mmol Mg/24 h. The ratio of median 24-hour urinary Ca for rainwater versus coastal groundwater drinkers was 0.72 (95% CI: 0.64, 0.80). Rainwater drinkers had 2.15 (95% CI: 1.02, 3.27) mm Hg higher systolic BP, 1.82 (95% CI: 1.19, 2.54) mm Hg higher diastolic BP, 0.59 (95% CI: 0.17, 1.01) mmol/L higher FBG and -2.02 (95% CI: -5.85, 0.81) mg/dl change in high-density lipoprotein cholesterol compared with the coastal groundwater drinkers. Drinking rainwater was associated with worse cardiometabolic health measures, which may be due to the lower intake of salubrious Ca, Mg and K.

Tracking progress towards Target 6.1 of the United Nations Sustainable Development Goals, "achieving universal and equitable access to safe and affordable drinking water for all", necessitates the development of simple, inexpensive tools to monitor water quality. The rapidly growing field of synthetic biology has the potential to address this need by taking DNA-encoded sensing elements from nature and reassembling them to create field-deployable 'biosensors' that can detect pathogenic or chemical water contaminants. Here we describe water quality monitoring strategies enabled by synthetic biology and compare them to previous approaches used to detect three priority water contaminants: fecal pathogens, arsenic, and fluoride in order to explain the potential for engineered biosensors to simplify and decentralize water quality monitoring. We also briefly discuss expanding biosensors to detect emerging contaminants including metals and pharmaceuticals. We conclude with an outlook on the future of biosensor development, in which we discuss adaptability to emerging contaminants, outline current limitations, and propose steps to overcome the field's outstanding challenges to facilitate global water quality monitoring.

Unsafe drinking water remains a major cause of mortality and morbidity. While Rwanda's Community-Based Environmental Health Promotion Programme (CBEHPP) promotes boiling and safe storage, previous research found these efforts to be ineffective in reducing fecal contamination of drinking water. We conducted a cluster randomized control led trial to determine if adding a household water filter with safe storage to the CBEHPP would improve drinking water quality and reduce child diarrhea. We enrolled 1,199 households with a pregnant person or child under 5 across 60 randomly selected villages in Rwamagana district. CBEHPP implementers distributed and promoted water purifiers to a random half of villages. We conducted two unannounced follow-up visits over 13-16 months after the intervention delivery. The intervention reduced the proportions of households with detectable in drinking water samples (primary outcome) by 20% (PR 0.80, 95% CI 0.74-0.87,  < 0.001) and with moderate and higher fecal contamination (≥10 CFU/100 mL) by 35% (PR 0.65, 95% CI 0.57-0.74 < 0.001). The proportion of children under 5 experiencing diarrhea in the last week was reduced by 49% (aPR 0.51, 95%CI 0.35-0.73,  < 0.001). Our findings identify an effective intervention for improving water quality and child health that can be added to the CBEHPP.

Nitrate and microbial contamination of groundwater can occur in countries that face intense urbanization and inadequate sanitation. When groundwater is the main drinking water source, as is often the case in such countries, the need to remove these contaminants becomes acute. The combination of two technologies is proposed here, a biological step to denitrify and an electrochemical step to disinfect the groundwater, thereby aiming to reduce the chemical input and the footprint of groundwater treatment. As such, a pyrite-based fluidized bed reactor (P-FBR) was constructed to autotrophically denitrify polluted groundwater. The P-FBR effluent was disinfected in an electrochemical cell with electrogenerated Cl. Nitrate was removed with 79% efficiency from an initial 178 mg NO L at an average denitrification rate of 171 mg NO L d, with 18 h hydraulic retention time (HRT). The electrochemical unit achieved a 3.8-log reduction in total coliforms with a 41.7 A h m charge density.

There is evidence that increasing the consumption of water containing magnesium can improve glucose metabolism and insulin resistance in patients with type 2 diabetes mellitus (T2DM). This trial was undertaken with the objective of evaluating the effect of adding different concentrations of magnesium chloride to the desalinated drinking water on the glycemic, metabolic, and insulin resistance parameters among patients with T2DM. A randomized cross-sectional controlled clinical trial was conducted to evaluate the effects of adding magnesium chloride supplement to desalinated drinking water consumed by patients with T2DM on the glycemic and metabolic parameters and indicators of insulin sensitivity. The total number of patients with T2DM who successfully completed the trial is 102. Patients were randomly allocated into three groups: the first group received bottled water without added magnesium (0 mg/L) (Group A,  = 37); the second group received bottled water with a low level of magnesium (20 mg/L) (Group B,  = 33); and the third group received drinking water with a high level of magnesium (50 mg/L) (Group C,  = 32). The daily consumption of elemental magnesium for a period of 3 months resulted in significant improvement in HbA1C (8.0 vs 8.2%,  = 0.04), insulin level (7.5 vs 9.9 μIU/mL,  = 0.03), and homeostasis model assessment-estimated insulin resistance (HOMA.IR) (2.5 vs 2.9,  = 0.002) in group C. However, there was no significant improvement in fasting blood glucose (FBS) level or lipid profile. The results of this study suggest that oral magnesium supplementation at the given dose of 50 mg/L daily added to drinking water could improve long-term glycemic control indicators and reduce insulin resistance in patients with T2DM.

For emerging economies lacking public budgets, continuous improvement of urban wastewater treatment efficiency (UWTE) requires effective government supervision of wastewater treatment infrastructures (WTIs) and participation of private capital seeking to profit-maximising. However, to what extent this public-private partnership (PPP) model, aimed at a reasonable sharing of benefit and risk, in delivering WTIs can improve the UWTE is unknown. We evaluated the impact of the PPP model on the UWTE by collecting data from 1303 urban wastewater treatment PPP projects in 283 prefecture-level cities in China from 2014 to 2019 and used data envelopment analysis and Tobit regression model. The UWTE was significantly higher in prefecture-level cities that introduced the PPP model in the construction and operation of WTIs, particularly those with a feasibility gap subsidy, competitive procurement, privatised operation, and non-demonstration. Moreover, the effects of PPPs on UWTE were limited by the economic development level, marketisation, and climatic conditions.

Geogenic fluoride contaminates the water of tens of millions of people. However, many are unaware of the fluoride content due in part to shortcomings of detection methods. Biosensor tests are a relatively new approach to water quality testing that address many of these shortcomings but have never been tested by non-experts in a "real-world" setting. We therefore sought to assess the accuracy and usability of a point-of-use fluoride biosensor using surveys and field tests in Nakuru County, Kenya. Biosensor tests accurately classified elevated fluoride (≥1.5 ppm) in 89.5% of the 57 samples tested. Usability was also high; all participants were able to use the test and correctly interpreted all but one sample. These data suggest that biosensor tests can provide accurate, meaningful water quality data that help non-experts make decisions about the water they consume. Further scaling of these technologies could provide new approaches to track global progress towards Sustainable Development Goal 6.

Water scarcity and droughts are an increasing issue in many parts of the world. In the context of urban water systems, the transition to circularity may imply wastewater treatment and reuse. Planning and assessment of water reuse projects require decision-makers evaluating the cost and benefits of alternative scenarios. Manual or semi-automatic approaches are still common practice for planning both drinking and reclaimed water distribution networks. This work illustrates a decision support tool that, based on open data sources and graph theory coupled to greedy optimization algorithms, is able to automatically compute the optimal reclaimed water network for a given scenario. The tool provides not only the maximum amount of served reclaimed water per unit of invested cost, but also the length and diameters of the pipes required, the location and size of storage tanks, the population served, and the construction costs, i.e., everything under the same architecture. The usefulness of the tool is illustrated in two different but complementary cities in terms of size, density, and topography. The construction cost of the optimal water reclaimed network for a city of approximately 100,000 inhabitants is estimated to be in the range of €0.17-0.22/m (for a payback period of 30 years).

The COVID-19 pandemic and associated prevention policies can directly or indirectly alter the sentiment of individuals while registering water pollution complaints, but observational evidence remains limited. Here, we conducted a sentiment analysis on over 10,000 water pollution complaints from residents in Alabama, USA (2012-2021) to better understand how and to what extent COVID-19 has altered emotion (polarity score-based) and attitude (subjectivity) of water pollution complaints. We found that the 2017 state-wise drought significantly increased the percentage of negative water pollution complaints by +35%, with no significant alternation in attitude before the COVID-19 pandemic. Since COVID-19, the percentage of negative and subjective water pollution complaints significantly decreased and increased by -30 and +20%, respectively, and these sentiment alternations were maintained by 2021. This study provides a new direction for environmental governance and management, requiring a timely response to changes in the public's emotions and attitudes during the next climate extremes and pandemics.

Rainwater harvesting reliability, the proportion of days annually when rainwater demand is fully met, is challenging to estimate from cross-sectional household surveys that underpin international monitoring. This study investigated the use of a modelling approach that integrates household surveys with gridded precipitation data to evaluate rainwater harvesting reliability, using two local-scale household surveys in rural Siaya County, Kenya as an illustrative case study. We interviewed 234 households, administering a standard questionnaire that also identified the source of household stored drinking water. Logistic mixed effects models estimated stored rainwater availability from household and climatological variables, with random effects accounting for unobserved heterogeneity. Household rainwater availability was significantly associated with seasonality, storage capacity, and access to alternative improved water sources. Most households (95.1%) that consumed rainwater faced insufficient supply of rainwater available for potable needs throughout the year, with intermittencies during the short rains for most households with alternative improved sources. Although not significant, stored rainwater lasts longer for households whose only improved water source was rainwater (301.8 ± 40.2 days) compared to those having multiple improved sources (144.4 ± 63.7 days). Such modelling analysis could enable rainwater harvesting reliability estimation, and thereby national/international monitoring and targeted follow-up fieldwork to support rainwater harvesting.

Halfway through the Sustainable Development Goal (SDG) period, there has been little research on the criteria for monitoring safely managed sanitation under SDG target 6.2. For reporting against SDGs, global indicators are necessarily limited and exclude many safety aspects from a public health perspective. Primary survey data from 31,784 households in seven countries in Asia and Africa were analysed, comparing estimates of safely managed on-site sanitation based on global indicators with five complementary indicators of safety: animal access to excreta, groundwater contamination, overdue emptying, entering containments to empty and inadequate protection during emptying. Application of additional criteria reduced the population with safely managed sanitation by 0.4-35% for specific indicators, with the largest impact due to the risk of groundwater contamination, animal access, and containments overdue for emptying. Combining these indicators across the service chain, excluding transport and treatment, found almost three-quarters of on-site systems currently assessed as safely managed with global indicators were considered unsafe based on complementary indicators. A more comprehensive assessment of safety of on-site sanitation can be achieved through these indicators, which could be integrated into national monitoring systems and used to inform sanitation investments that address local health-related risks.

Quality improvements and reduction of disease risk for low-resource shared sanitation facilities require cleanliness assessment approaches that are both rigorous and practical. Using Adenosine Triphosphate (ATP) bioluminescence testing, we assessed contamination on high-touch (HT) surfaces (inner door handles) at 32 shared toilet sites in Kisumu, Kenya. In public toilets, contamination was lowest after cleaning and disinfection (C&D) with 0.5% chlorine solution (adjusted difference in mean log Relative Light Units per 100cm (aDiff): -1.61; CI: -2.43, -0.59), followed by C&D with 0.1% chlorine solution (aDiff: -1.16; CI: -1.77, -0.55). ATP levels were not associated with overall observable toilet cleanliness and had poor agreement with visually assessed HT surface cleanliness. Our findings demonstrate the utility of this field-feasible method for detecting the impact of recent C&D in low-resource shared toilets, a novel setting for ATP cleanliness testing, while also highlighting the importance of using effective C&D procedures and addressing HT surfaces within cleaning protocols.