Table 1.

Suggested criteria for ideal integrity monitoring systems or devices.

Criteria	Requirement(s)
Technique Considerations
Test type	Test should be online and provide integrity performance (LRV) results in real-time. Detection in permeate from membrane elements, individual pressure vessels or membrane array of complete membrane train. System shutdown unnecessary, normal operations continue during integrity surveillance.
Sensitivity	High sensitivity at low challenge species concentration.
Selectivity	Challenge species should be representative of the smallest virus rather than chemical compounds and not be subject to changes in detection resulting from variations in environmental or chemical conditions such as NOM, salinity, pH and temperature.
Output	Test should deliver minimum LRV of 4 log10 sensitivity.
Financial Considerations
Capital cost	In the same order or less of capital cost as existing online real-time systems such as total organic carbon instrumentation.
Installation Integration	The ability to be fully integrated into existing systems as well as new systems seamlessly (greenfield and brownfield applications).
Operation	Should require minimal training for operators.
Running costs	Should not add more than 1–1.5% of the tariff charged to consumers for the provision of treated water.