Field assessment of bacterial communities and total trihalomethanes: Implications for drinking water networks

Operation and maintenance (O&M) of drinking water distribution networks (DWDNs) in tropical countries simultaneously face the control of acute and chronic risks due to the presence of microorganisms and disinfection by-products, respectively. In this study, results from a detailed field characterization of microbiological, chemical and infrastructural parameters of a tropical-climate DWDN are presented. Water physicochemical parameters and the characteristics of the network were assessed to evaluate the relationship between abiotic and microbiological factors and their association with the presence of total trihalomethanes (TTHMs). Illumina sequencing of the bacterial 16s rRNA gene revealed significant differences in the composition of biofilm and planktonic communities. The highly diverse biofilm communities showed the presence of methylotrophic bacteria, which suggest the presence of methyl radicals such as THMs within this habitat. Microbiological parameters correlated with water age, pH, temperature and free residual chlorine. The results from this study are necessary to increase the awareness of O&M practices in DWDNs required to reduce biofilm formation and maintain appropriate microbiological and chemical water quality, in relation to biofilm detachment and DBP formation

Drinking water temperature around the globe : understanding, policies, challenges and opportunities

Water temperature is often monitored at water sources and treatment works; however, there is limited monitoring of the water temperature in the drinking water distribution system (DWDS), despite a known impact on physical, chemical and microbial reactions which impact water quality. A key parameter influencing drinking water temperature is soil temperature, which is influenced by the urban heat island effects. This paper provides critique and comprehensive summary of the current knowledge, policies and challenges regarding drinking water temperature research and presents the findings from a survey of international stakeholders. Knowledge gaps as well as challenges and opportunities for monitoring and research are identified. The conclusion of the study is that temperature in the DWDS is an emerging concern in various countries regardless of the water source and treatment, climate conditions, or network characteristics such as topology, pipe material or diameter. More research is needed, especially to determine (i) the effect of higher temperatures, (ii) a legislative limit on temperature and (iii) measures to comply with this limit

MUISKA: multidimensional approach for risk assessment of an intermittent water system

Despite its vast reach, the term water security remains challenging to ground into actionable daily water risk scenarios. From its introduction 20 years ago by the ministerial Declaration of The Hague on Water, to its adoption by development actors, water professionals, academia, and governments–various theories, methodologies, and approaches have been published. Failures to advance SDG6 signal a clear need for an approach that includes multiple water-security risks at basin level to improve water and land planning. Here we present MUISKA, MUltidimensional rISK Assessment, an approach to assess and compare multiple water-security risks at basin level. In this paper, we explore the development of the first three steps of this approach by the identification of water service perceptions using surveys in Cajibío, a municipality highly affected by the armed conflict in Colombia. The MUISKA approach allowed us the identification of intermittent water supply as an important and complex water security issue in Cajibío. Based on multiple-actor participation, systems perspective, and notions of hydrocomplexity, MUISKA facilitated the documentation and assessment of complex and competing water-security scenarios