Water validation

how can we decide the point frequency during III phase analysis of water system for Purified and Water for injection and any reference is there than mentioned here.

Frequency of sampling basically depends upon the results obtained and where the counts/endotoxin observed are higher than other days of testing.
Note: The point of generation of purified water and return loop shall be monitored in daily basis.
Also, it depens upon company policies and management, so as to maintain the quality of water as per requirement.
Some company follow sampling to be done in such a way that all the points is covered in 15 days, 1 month or 2 months.