“Alkaline” water refers to water with a pH (hydrogen potential) of more than 7.0 on the pH spectrum. The pH level is a number that measures how acidic or alkaline a substance is on a scale of 0 to 14. A pH of 1 to 7 is considered acidic while anything over 7.0 is alkaline. The 'normal' range is 7.35 - 7.45 for arterial blood.