Globally, millions lack access to improved sanitation and drinking water, leading to preventable diseases and deaths, particularly among children under five. While source water quality is important, contamination frequently occurs at the point of consumption, highlighting the need for household-level interventions. The UN Children's Fund (UNICEF) and Joint Monitoring Programme (JMP) emphasize the importance of monitoring safe drinking water management. Ecuador, with diverse geographic regions and a fragmented water service provision system, faces unique challenges in ensuring water quality. The National Secretary of Water (SENAGUA) and the Agency for the Water Regulation and Control (ARCA) govern and regulate the sector, but service quality is diverse across the country's 221 municipal governments and approximately 7,000 community water service providers. The Ecuadorian Service for Normalization (INEN) sets the standard (INEN 1108) for potable water, yet implementation of a clear framework for water quality control and surveillance has been lacking. In 2016, Ecuador’s National Institute of Statistics and Censuses (INEC), supported by the World Bank Group, UNICEF, and WHO/UNICEF JMP, integrated water quality testing into its National Survey on Employment, Unemployment, and Subemployment (ENEMDU), initially testing source water quality. This was followed by a second survey in 2019, which extended testing to include point-of-consumption water samples. The study detailed here analyzes these datasets to understand the challenges to achieving SDG 6.1 (clean water and sanitation) and inform sector policies.

The introduction adequately cites relevant reports from UNICEF and WHO, emphasizing the global burden of waterborne diseases and the importance of monitoring water quality at the point of consumption. It highlights the lack of a comprehensive water quality control and surveillance framework in Ecuador, despite the existence of a national standard (INEN 1108). The reference to the Multiple Indicator Cluster Surveys (MICS) methodology employed by UNICEF provides context for Ecuador's survey design. The fragmented nature of water service provision in Ecuador, with numerous municipal and community providers, is discussed as a significant challenge to effective monitoring and regulation. While the introduction serves as a literature review by summarizing existing knowledge, a more detailed and explicit literature review section separating this discussion from other contextual elements would have strengthened the paper.

The study utilized data from Ecuador’s 2016 and 2019 ENEMDU surveys, which included water quality testing (presence/absence of *E. coli*) for subsamples of households. The 2019 survey collected samples from both the water source and the point of consumption. Administrative records from the 2016 and 2017 Census of Municipalities (CGADs) and reports from community water providers to the Water Regulation and Control Agency (ARCA) were also incorporated. Meteorological data from the Guayaquil meteorological station were used to analyze potential seasonal influences on water quality. The safely managed drinking water indicator was defined according to national guidelines, incorporating source type, quality, accessibility, and availability. Data analysis included hypothesis testing, Kernel regression to assess the relationship between safe water access and income, and Shapley values to determine the contribution of each component to the safely managed drinking water indicator. A logistic regression model with Huber-White estimators was employed to analyze factors associated with water quality at the point of consumption, categorizing factors as immediate, extended, and social. Data linking was performed between administrative records and survey data to trace water contamination along the service chain. The Colitag™ water test was used to detect *E. coli* in water samples. The authors note limitations to analysis related to the data collection period influencing comparative results.

Key findings include: (1) A significant decrease in water quality at the source between 2016 and 2019, particularly in the coastal region and rural areas, potentially influenced by higher rainfall in 2019. (2) Water quality at the source is the most significant barrier to access to safely managed drinking water in Ecuador. (3) Significant contamination of water occurs between the source and the point of consumption, emphasizing the importance of household water treatment and safe storage practices. (4) Household water treatment (boiling or other methods) significantly improves water quality at the point of consumption when the source water is contaminated. However, inconsistent or improper treatment, alongside unsafe storage and poor hygiene practices like a lack of handwashing with soap and open defecation, can negate the benefits of treatment, even with good source water. (5) Administrative records regarding service provider compliance with the INEN 1108 standard show similarities with household source water quality results, suggesting potential use of records as a partial substitute for water-quality testing, but with limitations. (6) Geographic location (particularly rural and Amazonian regions), ethnicity, and household head's education level show strong correlation with water quality at the point of consumption. Specific statistical data supporting these findings are included throughout the paper. Table 1 compares water, sanitation, and hygiene service levels between 2016 and 2019. Figures 2-5 visually illustrate the contributions of different factors to safe water access and water contamination along the service chain.

The findings confirm that water quality is the primary constraint on achieving safely managed drinking water access in Ecuador. This highlights the urgency of strengthening water quality control and surveillance efforts, including a risk-based approach focusing on parameters with significant public health implications. The strong effect of household water treatment when source water is contaminated underscores the importance of promoting proper water treatment and safe storage practices while also addressing associated hygiene factors. The study also demonstrates the potential for leveraging administrative records as a partial substitute for source water quality testing, while acknowledging the limitations of such an approach and the added value of point-of-consumption testing. The significant contamination between source and point of consumption emphasizes the need to include this critical element in SDG 6.1 monitoring. The observed seasonal influence on water quality warrants consideration of seasonal factors in water quality interventions and surveillance strategies. The study’s limitations, especially those regarding the comparability of 2016 and 2019 data due to differing data collection periods, should be considered when interpreting the results.

This study demonstrates the value of integrating water quality testing into national household surveys for monitoring progress toward SDG 6.1 and providing insights into the complexities of the water sector. The findings highlight the critical role of water quality as a primary barrier to access, the importance of household-level interventions, and the potential of using administrative records, alongside the necessity for point-of-consumption water testing. Future research could explore the reasons behind the limited effectiveness of household water treatment, investigate the use of additional indicators beyond E. coli contamination, and conduct seasonal monitoring to more accurately assess the impacts of various interventions. The study advocates for aligning national development plans with SDG 6.1 to effectively address water quality challenges in Ecuador.

The study's analysis of temporal trends between 2016 and 2019 data is limited by differences in the timing of the water-quality testing, with potential confounding influences from seasonal variations in rainfall. While administrative records offer a potential complement to direct water quality testing, their reliance on self-reporting from service providers introduces potential bias. The study focused solely on *E. coli* contamination and did not analyze other chemical contaminants, limiting the scope of water quality assessment. Finally, the survey data rely on self-reported household practices, potentially impacting the accuracy of reported water treatment and hygiene behaviors.