How often is it recommended to do chemical testing of a water system when performing a PQ.
we intend doing every point on days 1 ,5 ,6 and 10 of our 10 days full testing.
Is this deemed sufficient for an RO water system?
[quote=Austin Stewart]How often is it recommended to do chemical testing of a water system when performing a PQ.
we intend doing every point on days 1 ,5 ,6 and 10 of our 10 days full testing.
Is this deemed sufficient for an RO water system?[/quote]
Dear Austin,
For PQ of water system , it must be perform and monitor for one year in three phases, The performance of each major system component and all user points will be verified during phase I testing. This will be accomplished by sampling the system for entire one month and performing chemical analyses and microbiological evaluation on these samples.Phase II is a continuation of phase I but with reduced sampling frequency. Phase II will be initiated only after the requirements stipulated in the phase I testing have been satisfied. The evaluation of sampling and testing of this phase will take three months. Phase III is a continuation of phase II but with reduced sampling frequency .The evaluation of sampling and testing of this phase will take eight months. And data of entire one year including phase I and phase II data will presented graphically (trend analysis) and collecting the result as retrospective.
In Third phase it is recommended to reduce analysis to weekly basis, and even after finishing the third phase routine analysis is to be done at least once in a week. Sampling is prefered to be done on Friday, as in most pharmaceuticals Saturday and sunday is off. incase of Test results failure the batches which were produced during the gap should be subjected on Microbiological analysis.
What happened to 20 days? The last water system I did, of course it was in 2004, the requirement was for 20 days of PQ. We had debates on whether, it was 20 consecutive days or 5 days a week for 4 weeks. We settled on 20 consecutive days simply because we wanted to release the water for use in production. There was a silly requirement we felt was necessary to meet, validated utilities. So after we completed the PQ, we did a yearly monitoring program to baseline the system as the quality of the feed water changed(but not a PQ as we had no acceptance criteria). Also, the water system was/is monitored DAILY for routine analysis, we did/do a rotating sampling for each use point. As you can see our risk tolerance was low, 24 hours.
Dear Meyert,
Validation of water systems should consist of at least three phases:
Phase 1: investigational phase; Phase 2: short-term control; and Phase 3:
long-term control.
During the period following phase 3 (typically running for one year)
the objective should be to demonstrate that the system is under control over
a long period of time. Sampling may be reduced from, e.g. daily to weekly.
so it is better and recommended that the duration of PQ is one year including three phases, however the water can be used after getting one month successful results same as you done in 2004. 
Thanks
I agree with Shahnawaz.
With the change in seasons, water treatment chemicals etc, one must be sure that the water system can handle the changes over all 4 seasons, ie 1 year.
Hope that is of some help.