Performance of Community Water Board-Managed Passive In-Line Chlorinators Supported by a Circuit Rider Program in Rural Honduras.

This study evaluated the ability of passive chlorinators and the associated kinds of external support necessary to provide adequate free chlorine residual (FCR) for community distribution systems in rural Honduras. We found that 77% of samples, from distribution systems with passive chlorinators installed by EOS International at storage tanks within these distribution systems, had FCR concentrations that met or exceeded the World Health Organization minimum threshold of 0.2 mg/L for point-of-use or piped systems. In EOS-supported communities, passive chlorinators delivered FCR ≥ 0.2 mg/L in 90% of tank samples, 83% of middle-house samples, and 79% of last-house samples. Technical issues accounted for only 26% of all lapses in chlorination (i.e., FCR = 0 mg/L). Occasional and habitual errors of the local water board accounted for 24 and 15% of all lapses. Visit frequency by EOS circuit riders was strongly correlated with positive chlorination outcomes, and technical assistance visits were the most valuable of all visit types. It was also shown that monitoring visits were negatively correlated with other visit types, indicating that monitoring may take place at the expense of more valuable visit types, which highlights the potential need for remote FCR monitoring approaches.

Passive In-Line Chlorination for Drinking Water Disinfection: A Critical Review.

The world is not on track to meet Sustainable Development Goal 6.1 to provide universal access to safely managed drinking water by 2030. Removal of priority microbial contaminants by disinfection is one aspect of ensuring water is safely managed. Passive chlorination (also called in-line chlorination) represents one approach to disinfecting drinking water before or at the point of collection (POC), without requiring daily user input or electricity. In contrast to manual household chlorination methods typically implemented at the point of use (POU), passive chlorinators can reduce the user burden for chlorine dosing and enable treatment at scales ranging from communities to small municipalities. In this review, we synthesized evidence from 27 evaluations of passive chlorinators (in 19 articles, 3 NGO reports, and 5 theses) conducted across 16 countries in communities, schools, health care facilities, and refugee camps. Of the 27 passive chlorinators we identified, the majority (22/27) were solid tablet or granular chlorine dosers, and the remaining devices were liquid chlorine dosers. We identified the following research priorities to address existing barriers to scaled deployment of passive chlorinators: (i) strengthening local chlorine supply chains through decentralized liquid chlorine production, (ii) validating context-specific business models and financial sustainability, (iii) leveraging remote monitoring and sensing tools to monitor real-time chlorine levels and potential system failures, and (iv) designing handpump-compatible passive chlorinators to serve the many communities reliant on handpumps as a primary drinking water source. We also propose a set of reporting indicators for future studies to facilitate standardized evaluations of the technical performance and financial sustainability of passive chlorinators. In addition, we discuss the limitations of chlorine-based disinfection and recognize the importance of addressing chemical contamination in drinking water supplies. Passive chlorinators deployed and managed at-scale have the potential to elevate the quality of existing accessible and available water services to meet "safely managed" requirements.

Land use influences stream bacterial communities in lowland tropical watersheds.

Land use is known to affect water quality yet the impact it has on aquatic microbial communities in tropical systems is poorly understood. We used 16S metabarcoding to assess the impact of land use on bacterial communities in the water column of four streams in central Panama. Each stream was influenced by a common Neotropical land use: mature forest, secondary forest, silvopasture and traditional cattle pasture. Bacterial community diversity and composition were significantly influenced by nearby land uses. Streams bordered by forests had higher phylogenetic diversity (Faith's PD) and similar community structure (based on weighted UniFrac distance), whereas the stream surrounded by traditional cattle pasture had lower diversity and unique bacterial communities. The silvopasture stream showed strong seasonal shifts, with communities similar to forested catchments during the wet seasons and cattle pasture during dry seasons. We demonstrate that natural forest regrowth and targeted management, such as maintaining and restoring riparian corridors, benefit stream-water microbiomes in tropical landscapes and can provide a rapid and efficient approach to balancing agricultural activities and water quality protection.