Water Distribution System Deficiencies and Gastrointestinal Illness: A Systematic Review and Meta-Analysis. Env Health Perspec, Mar 2014.
Authors: Ayse Ercumen, Joshua S. Gruber, and John M. Colford Jr.
Background: Water distribution systems are vulnerable to performance deficiencies that can cause (re)contamination of treated water and plausibly lead to increased risk of gastrointestinal illness (GII) in consumers.
Objectives: It is well established that large system disruptions in piped water networks can cause GII outbreaks. We hypothesized that routine network problems can also contribute to background levels of waterborne illnessand conducted a systematic review and meta-analysis to assess the impact of distribution system deficiencies on endemic GII.
Methods: We reviewed published studies that compare direct tap water consumption to consumption of tap water re-treated at the point of use (POU) and studies of specific system deficiencies such as breach of physical or hydraulic pipe integrity and lack of disinfectant residual.
Results: In settings with network malfunction, consumers of tap versus POU-treated water had increased GII (incidence density ratio (IDR) = 1.34; 95% CI: 1.00, 1.79). The subset of non-blinded studies showed a significant association between GII and tap versus POU-treated water consumption (IDR = 1.52; 95% CI: 1.05, 2.20), but there was no association based on studies that blinded participants to their POU water treatment status (IDR = 0.98; 95% CI: 0.90, 1.08). Among studies focusing on specific network deficiencies, GII was associated with temporary water outages (relative risk = 3.26; 95% CI: 1.48, 7.19) as well as chronic outages in intermittently operated distribution systems (odds ratio = 1.61; 95% CI: 1.26, 2.07).
Conclusions: Tap water consumption is associated with GII in malfunctioning distribution networks. System deficiencies such as water outages also are associated with increased GII, suggesting a potential health risk for consumers served by piped water networks.