The challenge of achieving safely managed drinking water supply on San Cristobal island, Galápagos

The challenge of achieving safely managed drinking water supply on San Cristobal island, Galápagos

Publication Year:
Grub, Alyssa M.; Stewart, Jill R.; Ochoa-Herrera, Valeria
Resource Type:
Journal Article
This study found that in-line chlorination can improve household stored drinking water quality and reduce child diarrhoea in low-income urban settings with intermittent water supply.
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Achievement of United Nations Sustainable Development Goal 6.1 centers on the availability of a safely managed drinking water source for all. However, meeting the criteria for this goal is challenging on island systems and elsewhere with limited freshwater supplies. We measured microbial and chemical water quality over three years on San Cristobal Island, Galapagos, an island with limited freshwater supply, necessitating use of cisterns or roof tanks to ensure water availability in households. Our results showed that the municipal water treatment plants generally produced high quality drinking water but detection of Escherichia coli in 2-30% of post-treatment distribution samples suggests contamination and/or regrowth during distribution and storage. Linear regression revealed a modest, negative relationship between residual chlorine and microbial concentrations in drinking water samples, while 24-h antecedent rainfall only slightly increased microbial counts. Taken together, our results underscore the challenge of providing a safely managed drinking water source where limited freshwater quantities result in intermittent flow and require storage at the household level. Efforts to meet sustainable development goals for island systems will likely need to consider water availability for any treatment technologies or programs aimed at meeting water quality goals.

Resource Type

Journal Article

Publication Year



Grub, Alyssa M.; Stewart, Jill R.; Ochoa-Herrera, Valeria



Relevant Country


Specific Contaminants

Bacteria, Escherichia coli, Total coliform

University Affiliation

UNC Water Institute, Universidad San Francisco de Quito

Business Connect Takeaways

The COVID-19 pandemic has highlighted the importance of access to safe water and sanitation for preventing the spread of infectious diseases, particularly in low- and middle-income countries where many people lack basic services.
Community-led total sanitation (CLTS) is a participatory approach to promoting sanitation and hygiene behavior change, which has been widely implemented in many countries. However, the effectiveness of CLTS in achieving sustained behavior change and health outcomes is still debated, and there is a need for more rigorous evaluation and adaptation of the approach.
The authors propose a framework for integrating CLTS with water safety planning (WSP), which is a risk-based approach to ensuring the safety of drinking water from source to tap. This integrated approach could help to address the complex and interrelated challenges of water, sanitation, and hygiene (WASH) in a more holistic and sustainable way, by engaging communities in identifying and managing risks to their water supply and promoting behavior change for safe water use and sanitation.

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