Why "improved" water sources are not always safe.

Existing and proposed metrics for household drinking-water services are intended to measure the availability, safety and accessibility of water sources. However, these attributes can be highly variable over time and space and this variation complicates the task of creating and implementing simple and scalable metrics. In this paper, we highlight those factors - especially those that relate to so-called improved water sources - that contribute to variability in water safety but may not be generally recognized as important by non-experts. Problems in the provision of water in adequate quantities and of adequate quality - interrelated problems that are often influenced by human behaviour - may contribute to an increased risk of poor health. Such risk may be masked by global water metrics that indicate that we are on the way to meeting the world's drinking-water needs. Given the complexity of the topic and current knowledge gaps, international metrics for access to drinking water should be interpreted with great caution. We need further targeted research on the health impacts associated with improvements in drinking-water supplies.

Les indicateurs existants et proposés pour la distribution de l'eau potable des ménages visent à mesurer la disponibilité, la salubrité et l'accessibilité des sources d'eau. Cependant, ces caractéristiques peuvent être très variables dans le temps et l'espace, et ces variations compliquent la tâche de création et de mise en œuvre d'indicateurs simples et extensibles. Dans le présent article, nous mettons l'accent sur ces facteurs ­ en particulier, sur ceux qui concernent les sources d'eau soi-disant améliorées ­ qui contribuent à la variabilité de la salubrité de l'eau, mais qui peuvent ne pas être perçus généralement comme importants par les non-spécialistes. Les problèmes d'approvisionnement en eau, en quantité suffisante et en qualité satisfaisante ­ ces problèmes interdépendants sont souvent influencés par le comportement des hommes ­ peuvent contribuer à un risque accru d'être en mauvaise santé. Ce risque peut être masqué par les indicateurs globaux de l'eau qui indiquent que nous sommes en bonne voie de répondre aux besoins en eau potable de la planète. Compte tenu de la complexité du sujet et des lacunes des connaissances actuelles, les indicateurs internationaux pour l'accès à l'eau portable doivent être interprétés avec une grande prudence. Nous avons besoin de recherches ciblées et plus approfondies sur les effets sanitaires des améliorations dans le domaine de l'approvisionnement en eau potable.

Las mediciones existentes y propuestas para los servicios de agua potable de los hogares pretenden considerar la disponibilidad, seguridad y accesibilidad de las fuentes de agua. No obstante, estas características pueden variar mucho a lo largo del tiempo y del espacio, lo que complica la tarea de crear y poner en práctica mediciones sencillas y ampliables. En este documento destacamos los factores, en particular los relacionados con las llamadas fuentes de agua mejoradas, que contribuyen a la variabilidad de la seguridad del agua pero que, por lo general, los legos no identifican como importantes. Los problemas en el suministro de agua en cantidad y calidad suficientes, problemas interrelacionados en los que el comportamiento humano influye a menudo, pueden contribuir a un mayor riesgo de problemas sanitarios. Ese riesgo puede quedar oculto por mediciones de agua globales que indican que vamos camino de satisfacer las necesidades de agua potable en el mundo. Dada la complejidad del tema y las lagunas de conocimiento actuales, las mediciones internacionales sobre el acceso al agua potable deberían interpretarse con mucha cautela. Necesitamos más investigaciones específicas sobre el impacto sanitario asociado a las mejoras de los suministros de agua potable.

Water quality perceptions and willingness to pay for clean water in peri-urban Cambodian communities.

This paper studies household demand for improved water quality in peri-urban Cambodia, with particular attention paid to the influence of water quality on willingness to pay (WTP). Utilizing data from 915 household surveys, we analyze responses to a contingent valuation scenario using multivariate logit regression techniques that account for subjective perceptions of water quality. We estimate a mean household WTP for improved water quality of US$3 (roughly 1.2% of mean income) per month for households in this sample. We also find that the majority of households believe that their in-house water after storage, handling, and treatment is safe to drink. Furthermore, beliefs about existing levels of water quality have a significant impact on WTP for improved water quality. However, while perceptions of quality (and thus WTP) are highly related to taste preferences, actual water quality is relatively uncorrelated with water quality perceptions. These findings suggest that interventions aiming to increase the adoption of water treatment should account for underlying perceptions of water quality.

Disinfection of waterborne coliform bacteria using Luffa cylindrica fruit and seed extracts.

This study examined the potential of extracts of the plant Luffa cylindrica to act as disinfectants of drinking water. Aqueous extracts of the seeds and fruit of L. cylindrica were tested against total and faecal coliform bacteria in surface water by varying the extract doses and contact times. Inactivation of both faecal coliforms and total coliforms was highly variable and dose-dependent. The maximum coliform inactivation achieved in any trial was 86%. Fruit extracts were more successful at inactivating total coliforms than faecal coliforms. Seed extracts achieved higher coliform inactivation levels than fruit extracts generally. Overall, the antimicrobial potential of seeds and fruit from L. cylindrica was demonstrated; however the disinfection performance was less than would be required for these extracts to be considered reliable disinfectants for drinking water treatment.