Research papersRelevance of hydrological variables in water-saving efficiency of domestic rainwater tanks: Multivariate statistical analysis

•Relevance of hydrological variables in the study of rainwater-tank efficiency.•Multivariate statistical analysis to define the most relevant hydrological variables.•The average annual rainfall and PCD best represent rainfall regime in our region.•A precipitation temporal variability variable is necessary in empirical models.

This research investigated the relevance of four hydrological variables in the performance of a domestic rainwater harvesting (DRWH) system. The hydrological variables investigated are average annual rainfall (P), precipitation concentration degree (PCD), antecedent dry weather period (ADWP), and ratio of dry days to rainy days (nD/nR). Principal component analyses are used to group the water-saving efficiency into a select set of variables, and the relevance of the hydrological variables in a water-saving efficiency system was studied using canonical correlation analysis. The P associated with PCD, ADWP, or nD/nR attained a better correlation with water-saving efficiency than single P. We conclude that empirical models that represent a large combinations of roof-surface areas, rainwater-tank sizes, water demands, and rainfall regimes should also consider a variable for precipitation temporal variability, and treat it as an independent variable.