Risk Based Inspection (RBI) – Schedule M Point 4.12 (Purified Water used for WFI)
In a risk based inspection, Schedule M point 4.12 focuses on verifying that the quality of Purified Water used for the preparation of Water for Injection (WFI) meets IP/BP/USP requirements. cdsco.gov.in RBI treats this as a high-impact utility control because any failure can directly affect sterility assurance, endotoxin control, and overall product quality.
During inspection, the first expectation is clear system mapping: PW generation method (RO/EDI/DM), storage tank design, distribution loop configuration, materials of construction, slopes, dead-legs, return velocity, sanitization approach, and points of use (especially those feeding WFI generation). Inspectors look for evidence that the system was qualified (DQ/IQ/OQ/PQ) and that critical parameters are justified by risk (e.g., temperature control, recirculation, filtration, UV/ozone if used).
Next, inspectors verify routine monitoring vs pharmacopeial limits: conductivity, TOC, microbiological count, and where applicable endotoxin control (often expected for WFI, but PW feeding WFI must also be tightly controlled to prevent biofilm and endotoxin build-up). Records must show defined sampling locations, frequency, aseptic sampling technique, and trained personnel. Results should be trended, with alert/action limits, and investigations triggered for excursions or adverse trends (not only failures).
RBI also checks sanitization and maintenance discipline—hot water/steam, ozone, chemical sanitization cycles, holding times, and post-sanitization monitoring. The inspector will ask for deviation/CAPA evidence, change controls (e.g., filter change, membrane replacement, loop modification), and proof that actions were effective.
Finally, inspectors confirm that data is complete, contemporaneous, and reviewable (logbooks, electronic records, audit trails, and second-person review), because utilities are continuous systems where weak documentation can hide chronic contamination risks. The RBI checklist explicitly asks inspectors to confirm this PW-to-WFI quality compliance to IP/BP/USP as part of GMP verification under Schedule M.