This publication provides guidance to water-sector decision makers and planners on how to deal with the quality dimension of groundwater resources management in the World Bank's client countries. There is growing evidence of increasing pollution threats to groundwater and some well-documented cases of irreversible damage to important aquifers. This guide has been produced in the belief that groundwater pollution hazard assessment must become an essential part of environmental best practice for water supply utilities. The guide is particularly relevant for the World Bank's Latin American and Caribbean Region, where many countries have initiated major changes to modernize their institutional and legal framework for water resources management, but may not yet have considered groundwater at the same level as surface water, because of lack of awareness and knowledge of groundwater issues and policy options.

O Brasil é o segundo maior produtor de carne de frango do mundo, e o primeiro em exportação. Tamanha importância leva à necessidade de um criterioso programa de biosseguridade, buscando impedir problemas sanitários que possam causar danos aos plantéis ou comprometer a qualidade do produto final. Um dos patógenos mais importantes na avicultura é a Salmonella spp., sendo a Salmonella Heidelberg (SH) um sorovar frequentemente isolado e que vem destacando-se por sua dificuldade de eliminação da cadeia avícola e seu potencial zoonótico. A água eletroquimicamente ativada (EA) é um composto bactericida produzido a partir da eletrólise de sal e água. Através de membranas de eletrólise, os geradores EA produzem um composto com cloro livre, ácido hipocloroso e outros radicais livres. Este método alternativo vem destacando-se por ser seguro e ambientalmente responsável para a redução da contaminação dos produtos. Sendo assim, o objetivo deste estudo foi avaliar a efetividade da EA frente a 30 isolados de S. Heidelberg nas concentrações de 5 ppm, 50 ppm e 200 ppm de cloro livre com tempo de contato de 5, 10 e 40 minutos a 4º C e 25º C. O método utilizado foi o de diluição, com teste de suspensão em células planctônicas, e a contagem bacteriana realizada através do método de Drop plate. Observou-se que nas três concentrações utilizadas, a SH foi sensível a água eletroquimicamente ativada, exceto na concentração de 5 ppm por 40 minutos. O tratamento de 5 ppm por 5 minutos obteve uma redução significativa (3,3x104 UFC/mL) quando comparada ao grupo controle (sem tratamento) (7,2x104 UFC/mL). Na concentração de 50 ppm, independentemente do tempo de contato, todos os isolados obtiveram uma diminuição significativa da contagem média bacteriana (1,1x104 UFC/mL), quando comparado ao grupo controle (5,1x104 UFC/mL). Na concentração de 200 ppm com 10 minutos de contato, houve uma redução significativa, sendo que dos 30 isolados de SH, apenas quatro foi observado crescimento bacteriano. Os resultados encontrados demonstraram que a EA é efetiva na redução de SH, podendo ser utilizada como composto antimicrobiano alternativo no setor avícola para controle deste patógeno. | Brazil is the second largest producer of chicken meat in the world, and the first one to export. Such importance leads to the need for a careful biosecurity program, seeking to prevent sanitary problems that may cause damage to the plants or compromise the quality of the final product. One of the most important pathogens in poultry farming is Salmonella spp., With Salmonella Heidelberg (SH) being a frequently isolated serovar that has been distinguished by its difficulty in eliminating the poultry chain and its zoonotic potential. Electrochemically activated water (EA) is a bactericidal compound produced from the electrolysis of salt and water. Through electrolysis membranes, EA generators produce a compound with free chlorine, hypochlorous acid and other free radicals. This alternative method has been noted for being safe and environmentally responsible for reducing contamination of products. Therefore, the objective of this study was to evaluate the effectiveness of EA against 30 S. Heidelberg isolates at concentrations of 5 ppm, 50 ppm and 200 ppm with contact time of 5, 10 and 40 minutes at 4ºC and 25ºC. The method used was the dilution, with suspension test in planktonic cells, and the bacterial count performed by the method of Drop plate. It was observed that in the three concentrations used, SH was sensitive to electrochemically activated water, except at the concentration of 5 ppm for 40 minutes. Treatment of 5 ppm for 5 minutes resulted in a significant reduction (3.3x104 CFU / mL) when compared to the control group (without treatment) (7.2x104 CFU / mL). At the concentration of 50 ppm, regardless of contact time, all the isolates had a significant decrease in the mean bacterial count (1.1x104 CFU / mL) when compared to the control group (5.1x104 CFU / mL). At the concentration of 200 ppm with 10 minutes of contact, there was a significant reduction, and of the 30 SH isolates, only four showed bacterial growth. The results showed that the EA is effective in the reduction of SH, and can be used as an alternative antimicrobial compound in the poultry sector to control this pathogen.

Legionella spp. is an environmental bacterium that can survive in a wide range of physicochemical conditions and may colonize distribution systems of drinking water and storage tanks. Legionella pneumophila is the major waterborne pathogen that can cause 90% of Legionnaires’ disease cases. The aim of this study was to detect the presence of Legionella spp. in household drinking water tanks in the city of Resistencia, Chaco. The detection of Legionella in water samples was performed by culture methods as set out in ISO 11731:1998. Thirty two water samples were analyzed and Legionella spp. was recovered in 12 (37.5%) of them. The monitoring of this microorganism in drinking water is the first step towards addressing the control of its spread to susceptible hosts.

Dissolved organic carbon (DOC) is composed of a diverse array of compounds, predominantly humic substances, and is a near ubiquitous component of natural groundwater, notwithstanding climatic extremes such as arid and hyper-arid settings. Despite being a frequently measured parameter of groundwater quality, the complexity of DOC composition and reaction behaviour means that links between concentration and human health risk are difficult to quantify and few examples are reported in the literature. Measured concentrations from natural/unpolluted groundwater are typically below 4 mg C/l, whilst concentrations above these levels generally indicate anthropogenic influences and/or contamination issues and can potentially compromise water safety. Treatment processes are effective at reducing DOC concentrations, but refractory humic substance reaction with chlorine during the disinfection process produces suspected carcinogenic disinfectant by-products (DBPs). However, despite engineered artificial recharge systems being commonly used to remove DOC from recycled treated wastewaters, little research has been conducted on the presence of DBPs in potable groundwater systems. In recent years, the capacity to measure the influence of organic matter on colloidal contaminants and its influence on the mobility of pathogenic microorganisms has aided understanding of transport processes in aquifers. Additionally, advances in polymerase chain reaction techniques used for the detection, identification, and quantification of waterborne pathogens, provide a method to confidently investigate the behaviour of DOC and its effect on contaminant transfer in aquifers. This paper provides a summary of DOC occurrence in groundwater bodies and associated issues capable of indirectly affecting human health.

This study examined the relative importance of climate change and drinking-water treatment for gastrointestinal illness incidence in children (age <5 years) from period 2046–2065 compared to 1991–2010. The northern Wisconsin (USA) study focused on municipalities distributing untreated groundwater. A time-series analysis first quantified the observed (1991–2010) precipitation and gastrointestinal illness associations after controlling for seasonality and temporal trends. Precipitation likely transported pathogens into drinking-water sources or into leaking water-distribution networks. Building on observed relationships, the second analysis projected how climate change and drinking-water treatment installation may alter gastrointestinal illness incidence. Future precipitation values were modeled by 13 global climate models and three greenhouse-gas emissions levels. The second analysis was rerun using three pathways: (1) only climate change, (2) climate change and the same slow pace of treatment installation observed over 1991–2010, and (3) climate change and the rapid rate of installation observed over 2011–2016. The results illustrate the risks that climate change presents to small rural groundwater municipalities without drinking water treatment. Climate-change-related seasonal precipitation changes will marginally increase the gastrointestinal illness incidence rate (mean: ∼1.5%, range: −3.6–4.3%). A slow pace of treatment installation somewhat decreased precipitation-associated gastrointestinal illness incidence (mean: ∼3.0%, range: 0.2–7.8%) in spite of climate change. The rapid treatment installation rate largely decreases the gastrointestinal illness incidence (mean: ∼82.0%, range: 82.0–83.0%).

Water quality affects many aspects of water availability, from precluding use to societal perceptions of fit-for-purpose. Pathogen source and transport processes are drivers of water quality because they have been responsible for numerous outbreaks resulting in large economic losses due to illness and, in some cases, loss of life. Outbreaks result from very small exposure (e.g., less than 20 viruses) from very strong sources (e.g., trillions of viruses shed by a single infected individual). Thus, unlike solute contaminants, an acute exposure to a very small amount of contaminated water can cause immediate adverse health effects. Similarly, pathogens are larger than solutes. Thus, interactions with surfaces and settling become important even as processes important for solutes such as diffusion become less important. These differences are articulated in “Colloid Filtration Theory”, a separate branch of pore-scale transport. Consequently, understanding pathogen processes requires changes in how groundwater systems are typically characterized, where the focus is on the leading edges of plumes and preferential flow paths, even if such features move only a very small fraction of the aquifer flow. Moreover, the relatively short survival times of pathogens in the subsurface require greater attention to very fast (<10 year) flow paths. By better understanding the differences between pathogen and solute transport mechanisms discussed here, a more encompassing view of water quality and source water protection is attained. With this more holistic view and theoretical understanding, better evaluations can be made regarding drinking water vulnerability and the relation between groundwater and human health.

A prerequisite for minimizing contamination risk whilst conducting managed aquifer recharge (MAR) with recycled water is estimating the residence time in the zone where pathogen inactivation and biodegradation processes occur. MAR in Western Australia’s coastal aquifers is a potential major water source. As MAR with recycled water becomes increasingly considered in this region, better knowledge of applied and incidental tracer-based options from case studies is needed. Tracer data were collected at a MAR site in Floreat, Western Australia, under a controlled pumping regime over a distance of 50 m. Travel times for bromide-spiked groundwater were compared with two incidental tracers in recycled water: chloride and water temperature. The average travel time using bromide was 87 ± 6 days, whereas the estimates were longer based on water temperature (102 ± 17 days) and chloride (98 ± 60 days). The estimate of average flow velocity based on water temperature data was identical to the estimate based on bromide within a 25-m section of the aquifer (0.57 ± 0.04 m day⁻¹). This case study offers insights into the advantages, challenges and limitations of using incidental tracers in recycled water as a supplement to a controlled tracer test for estimating aquifer residence times.