Toward a comprehensive explanatory model of reliance on alternatives to the tap: evidence from California's retail water stores

Building on a recent increase in scholarly attention to the problem of tap water mistrust and resulting negative health impacts, we examine the relationship between neighborhood reliance on tap water alternatives and a range of explanatory factors. We model retail water store locations as a proxy for reliance on tap water alternatives in urbanized neighborhoods across California. Our study is unique in its inclusion of variables representing both compliance with primary and secondary water quality standards by publicly regulated drinking water systems serving particular neighborhoods, other water system attributes and the socioeconomic characteristics of neighborhoods. The location of retail water stores in urbanized neighborhoods does not appear strongly related to observed measures of water quality. Secondary contamination shows a weak relationship to tap alternative reliance, and primary contamination was not correlated with higher levels of tap alternative reliance. On the other hand, our research suggests that other socioeconomic factors, particularly country of birth, are associated with the prevalence of more water stores. Increasing reliance on tap water likely requires measuring and addressing secondary contamination found in distributional systems and premise plumbing, and more aggressive public education campaigns.