The objective of this study is to define a consumption indicator (CI) for water that can be used as a reference for developing water conservation plans at public schools. The methodology followed consists of a historical water consumption data survey of all schools in Recife, Brazil, a registration survey of school buildings, the calculation of consumption indicators for the period 2012–2015, and finally, the calculation of reference indicators. The results obtained indicated a reference range for the CI of 13.0 ± 2.0 L/student/day for water considering the set of all school typologies, with a 95% confidence level. The analysis of the schools in groups, classified into four typologies, led to the following reference ranges: 11.5 ± 2.0 L/student/day for regular schools, 13.5 ± 3.5 L/student/day for extended period schools, 22.0 ± 6.0 L/student/day for full period schools, and 18.5 ± 6.5 L/student/day for technical schools. Through the use of a consumption indicator, schools with a limited supply of potable or above average water can be identified and specific actions can be developed to achieve a sustainable use of water in the school environment.