Time series study of weather, water quality, and acute gastroenteritis at Water Safety Plan implementation sites in France and Spain

Abstract

Water Safety Plans (WSPs), recommended by the World Health Organization since 2004, can help drinking water suppliers to proactively identify potential risks and implement preventive barriers that improve safety. Few studies have investigated long-term impacts of WSPs, such as changes in drinking water quality or public health; however, some evidence from high-income countries associates WSP implementation with a reduction in diarrheal disease. To validate the previously observed linkages between WSPs and health outcomes, this time series study examined site-specific relationships between water-related exposures and acute gastroenteritis rates at three locations in France and Spain, including the role of WSP status. Relationships between control or exposure variables and health outcomes were tested using Poisson regression within generalized additive models. Controls included suspected temporal trends in disease reporting. Exposures included temperature, precipitation, raw water quality, and finished water quality (e.g., turbidity, free chlorine). In France, daily acute gastroenteritis cases were tracked using prescription reimbursements; Spanish data aggregated monthly acute gastroenteritis hospital visits. The models identified several significant relationships between indicators of exposure and acute gastroenteritis. Lag times of 6–9 days (including transit time) were most relevant for hydrological indicators (related to precipitation, runoff, and flow) at the two French sites, indicative of viral pathogens. Flush events (defined as surface runoff after a two-week antecedent dry period) linked to nonpoint source pollution were associated with a 10% increase in acute gastroenteritis rates at one location supplied by surface water. Acute gastroenteritis rates were positively associated with elevated turbidity average or maximum values in finished water at locations supplied by both surface and groundwater, by about 4% per 1-NTU increase in the two-week moving average of daily maxima or about 10% per 0.1 NTU increase in the prior month’s average value. In some cases, risk appeared to be mitigated by WSP-related treatment interventions. Our results suggest drinking water exposure is associated with some potentially preventable gastrointestinal illness risk in high-income regions.

Assessing operational performance benefits of a Water Safety Plan implemented in Southwestern France

“…22 The operational performance and water quality compliance improvements observed in this study did not correspond to a reduced risk of acute gastroenteritis in the service area, 11 although the changes may have altered risks posed by turbidity levels. 6 Cyclical monitoring and evaluation in concert with external experts such as public health agencies can help ensure that well-intended efforts do not have unintended consequences, 23 and assist iterative improvement of the WSP.…”

“…6,11,13 The metropolitan drinking water system serves about 740,000 people across 23 towns, drawing from a combination of deep-protected groundwater and shallow groundwater under the influence of surface water. The area-wide system includes 102 groundwater extraction points, 140 drinking water treatment facilities, 50 treated water storage tanks, and approximately 3200 km of distribution pipes.…”

“…Qualitative results were compiled for a single location, which was not previously disaggregated and analyzed independently in other studies. 6,11,13 The data integration process focused on building and merging, seeking complementarity of measures. 15 The results were reviewed and validated via participatory ‘member checks’ by three management-level personnel at the water utility studied, permitting refinements to both the quantitative and qualitative data interpretation.…”

“…4 WSP evaluation models would benefit from clarification of the relationships among different evaluation indicators and the mechanisms by which determinants (barriers or facilitators) affect outcomes and impacts. 5,6 Furthermore, many jurisdictions lack standardized guidance on recommended WSP performance indicators, which would enable wide-scale comparison. 7 …”

Making Europe go from bottles to the tap: Political and societal attempts to induce behavioral change

“…They are transmitted via the fecal–oral route and are endemic to many animals (Garcés‐Sanchez, Wilderer, Munch, Horn, & Lebuhn, ; Slifko, Smith, & Rose, ). Most of the outbreaks in Europe were associated with contaminated surface water used for drinking water supply (e.g., caused by the entry of wastewater or polluted surface runoff during heavy rainfall) in combination with insufficient treatment (Böhmer & Resch, ; Carmena, Aguinagalde, Zigorraga, Fernández‐Crespo, & Ocio, ; Méndez et al, ; Setty et al, ). In Europe, on average, surface water is used for one third of drinking water supplies and two thirds are provided by ground water (Roccaro et al, ).…”