On-line TOC is not enough. All guides to water systems require standard D/I/OQ testing to be performed. following on from that, you require a 3-stage PQ:
Stage 1: 2 - 4 weeks intensive sampling from each sampling point (usually on a daily basis). Water from the system cannot be used during this stage. All samples must pass Pharmacopoeial testing requirements for Purified Water for pharma Purposes. In addition, tests need to be performed on water between each treatment stage (SDI, Hardness, Iron, Chlorine, etc). TOC testing here is usually performed off-line. On-line testing is, however; a good indication of the health of the system, and these records should also form part of the data evaluation.
Stage 2: Additional 4 - 6 weeks testing, using a less intensive sampling regime. This is usually based on data from Stage 1. All testing to pass requirements as per Stage 1. Water from the system may be used during this time. Maintenance routines, etc are also usually finalised during this stage.
Stage 3: System is officially handed over and Routine Monitoring is performed for a year following successful completion of Stage 2. By this stage, a less rigorous sampling routine will have been established which ensures that all points are tested at least once/week. Operation, Maintenance, Calibration, Sanitisation, etc routines/schedules are refined. Warning and action limits have been established from the first 4 - 8 weeks of testing. Testing is trended, summarised and finally written up as a validation report closing off the PQ. Included will be a summary of all OOS, Deviations, Change Controls, Maintenance Records, etc.
Hope this helps…