The US EPA has released the publication of  Ensuring Drinking Water Quality in Schools During and After Extended Closures

It provides guidance on maintaining drinking water quality during extended closures and recommends start-up procedures when reopening to ensure that drinking water is safe for consumption. 

The factsheet is part of the EPA 3Ts for Reducing Lead in Drinking Water in Schools and Child Care Facilities (3Ts) ToolKit, and includes information for schools that are served by or are public water systems (PWSs).