One embodiment provides a system, including: at least two water analyzers, wherein at least one of the at least two water analyzers is positioned upstream of a purification apparatus and wherein at least another of the at least two water analyzers is positioned downstream of the purification apparatus; at least one processor; and a memory device that stores instructions executable by the processor to: receive water analysis data from the at least two water analyzers, wherein the water analysis data comprises information related to membrane integrity; identify an algorithm for calculating membrane integrity based upon received data corresponding to system attributes; and calculate, using the identified algorithm, the membrane integrity based upon the received water analysis data. Other aspects are described and claimed.