An assessment of the costs and benefits of interventions aimed at improving rural community water supplies in developed countries

Abstract

We report a cost benefit analyses (CBA) for water interventions in rural populations of developed country sub-regions. A Bayesian belief network was used to estimate the cost benefit ratio using Monte Carlo simulation. Where possible we used input data from recently published primary research or systematic reviews. Otherwise variables were derived from previous work in the peer-reviewed or grey literature. For these analyses we considered the situation of people with small and very small community supplies that may not be adequately managed. For the three developed country sub-regions Amr-A (America region A), Eur-A (European region A) and Wpr-A (Western Pacific region A), we estimate the costs of acute diarrhoeal illness associated with small community supplies to be U$4671 million (95% CI 1721–9592), the capital costs of intervention to be US$13703 million (95% CI 6670–20735), additional annual maintenance to be US$804 million (95%CI 359–1247) and the CB ratio to be 2.78 (95%CI 0.86–6.5). However, we also estimated the cost of post infectious irritable bowel syndrome (IBS) following drinking water-associated acute gastroenteritis to be US$11896 million (95%CI 3118–22657). When the benefits of reduced IBS are added to the analysis the CB ratio increases to 9.87 (95%CI 3.34–20.49). The most important driver of uncertainty was the estimate of the cost of illness. However, there are very few good estimates of costs in improving management of small rural supplies in the literature.

Investments in drinking-water provision in rural settings are highly cost beneficial in the developed world. In the developed world, the CB ratio is substantially positive especially once the impact of IBS is included.

Introduction

Inadequate provision of safe drinking-water for rural inhabitants is not only a problem of low income countries but also affects the wealthiest countries. Many people in rural communities within developed countries will have access to an extension of the mains drinking-water systems into the countryside (WHO/Unicef, 2006). However, many people still access their water from small, often locally-owned systems. These small systems may vary in size from those that supply a single dwelling to that that supply 100 or more dwellings.

These small systems are often referred to as community water supplies. The second edition of the WHO guidelines for drinking-water quality (WHO, 2006) admitted that it was difficult to develop a precise definition of a “community water supply” and definitions vary between countries. These guidelines went onto comment that whilst it may be useful to base definitions on population size or the type of supply, it is often administration and management that set community supplies apart. Small community systems are increasingly reliant on the involvement of ordinary, often untrained and sometimes unpaid, community members in the administration and operation of their systems.

The microbiological quality of drinking-water from small rural systems is much worse than from large systems. This is illustrated by surveillance data of microbiological analyses of private water supplies in England and Wales where 37% of samples were positive for E. coli (Rutter et al., 2000, Yip Richardson et al., in press) compared to 0.1% of samples from mains water supplies (Drinking Water Inspectorate, 2007). In addition, people living in rural settings with small supplies are far more likely to experience an outbreak of infectious disease than people receiving their water from a large public utility. In England and Wales only about 0.5% of the total population is reliant on private supplies and yet 36% of all detected drinking-water outbreaks were associated with these supplies (Said et al., 2003).