Continuity in Drinking Water Supply

The benefits of having a continuous, piped supply of safe drinking water delivered to household premises are widely recognised. Piped supplies on premises not only reduce the time and effort required to collect water, and thereby increase the amount of water available for personal and domestic needs but also are more likely to provide water that meets required standards for drinking water quality. A recent systematic review of drinking water quality [1] confirmed that piped water supplies are less likely to be contaminated than other types of “improved” sources, such as hand pumps, protected wells, and springs. However, continuity of piped supplies—that is, the uninterrupted supply of water—and the associated health impacts, are under-studied. Two papers in this issue of PLOS Medicine each shed light on a particular aspect of continuity and are a very welcome addition to the literature. Jeandron and colleagues [2] show that in the city of Uvira, in the Democratic Republic of the Congo, there was a significant relationship between interruptions in the piped water supply and cases of suspected cholera. This association was seen even though many in the city used piped services indirectly (that is, they did not have household connections and used water from standposts and shared connections). The interruptions in the piped water supply thus represented a lost opportunity to protect a cholera-vulnerable population. In Hubli-Dharwad, in the state of Karnataka in India, Ercumen and colleagues [3] show that while upgrading the piped supply to provide continuous service for 10% of the population was associated with a notable reduction in typhoid among the poor in the beneficiary group, they did not find the expected decrease in diarrhoeal diseases. The paper suggests a number of possible reasons, including unhygienic storage of water due to the use of yard taps rather than taps in the house; the perceived threat of supply interruptions; heavy contamination of the immediate household environment due to widespread open defecation among children; and the continuing presence of open sewers. It is notable that the research in India found a strong relationship between the continuity of the supply and quality of the water delivered. Among water samples taken from households receiving a continuous supply, less than 1% did not comply with WHO guidelines for drinking water quality, compared with over one-third of samples in households that did not benefit from improvements and still had intermittent supply. The importance of continuous piped supply to households in order to protect health is clear. This link is not surprising given the engineering reality—that maintaining continuous positive pressure in a piped network and avoiding negative pressure at all costs prevents infiltration of contaminated soil water [4]. Continuous supply also removes the need to store water and makes water readily available for hygiene, such as handwashing. From a public health policy point of view, ideally, households should have continuous water supply, treated with chlorine, piped directly into the house, with accompanying improvements