PQ Purified water system

As promised 2 days back to a member in this blog, Iam enclosing this comprehensive PQ of purified water system.

[COLOR=“blue”]- Its almost ready to use draft format
-You must have xl sheet record all results make a Trend sheet and graphs and add as annexures in annexures page.
-Ask your vendor how to sanitize that equipment. Make a note of that procedure and make a SOP and attach.
-Calibrate all equipments and presssure guages.
-Number all attachments, ports, columns, pipes and give a direction of flow to all pipe lines and also know as per regulations what Material of Construction of pipelines or Tanks or Valves are suitable for your product.Make a note and mention in Qualification documents where ever necessary.
-Make sure your conductivity and PH meters which are working online are suitably qualified, Installed and Calibrated and make sure that their ports are connected properly with out any leaks or airbubbles entering into them.[/color]

Document what ever suitable for you and where ever necessary.There is nothing like over documentation. Every useful thing has a value.

Have a great sunday.


Water System PQ.doc (621.5 KB)

Very nice Mr Druga,

Another excellent post.

Really a good compilation.

Greetings !

Thanks-Durga, for sharing the excellent template.

Excellent document…

thank you very much

A well written comprehensive template for Purified water system PQ.

In my experience, Phase 2 is very important in any water system. This is because if there are improper and invalid sanitization procedures, the system will not give desired results for too long.
Activated carbon, cartridge filters and RO membranes are all prone to Biofilm formation, which once formed is much difficult to remove rather then prevention. Biofilm / microbial contamination is one of the main cause of out of spec TOC and in later stages it is difficult to pin point the root cause. This is the reason I spent more time validating and modifying sanitization procedures while qualification of the water system which included Feed water auto-chlorination and chlorine contact time with water (20 mins recommended), hot water sanitization (80’C) and back washing time estimation of sand and carbon filters.

Another simple test I would like to add for an ideal RO system is the ‘Silt Density Index’ (SDI). Apologies if this is already included in the protocol, if not I think it is worth mentioning.

SDI is determined online on RO feed water, i.e. feed water finally entering the RO membrane.

The following procedure is adopted:

P30 = [1 – (ti / tf) x 100] (Where P30 is the Percent plugging at 30 PSI)

SDI15 = P30 / 15

The initial time (ti) is noted for a given quantity of the water to be tested, usually 500 ml, to pass through a new 47mm dia. 0.45 micron rated membrane filter under a constant pressure of 30 psi. The test continues uninterrupted and the same measurement repeated at time (tf) at intervals of 5 minutes 10 minutes, and 15 minutes. The SDI index is calculated as the percentage decay in flow per unit time with the 15 minute value taken as the test standard.


SDI of <5: No pre-filtration is necessary.
SDI of 5-10: A media (sand-type) filter is required.
SDI of >10: A 2-stage media filtration is necessary - possibly with the aid of coagulants or settling tanks.

Thanks & Regards,

Our fellow friends asked me about Recirculation speed of Purified water and WFI in the water distribution line.

If we have a continuous Hot water distribution line or Ozonization line we can have speeds from 3 feet/sec to little higher.

If we do not have such hot distribution capability in systems it is better to have 5feet/second or little higher.

In some of the experiments done it was proved that a 1000 meters of such system with out hot water capability took 25 hours of time to clean all the particulate material with same diameter of distribution pipes.

One must understand that in these casses the Diameter must be constant at every point in the distribution loop of water systems.

Thank you very much. it has helped me a lot in water system qualification. once again thank you for your every excellent post which have been very useful for us.

Good one. Very comprehensive.

thanks, very helpfull

Excellent work, very comprehensive

Dear durga prasad,
in MLT Should we incubate plates for 5 days or 7 days for TYMC?

Dear sir,

Excellent draft for the PQ.its extremly useful for my water validation process.

Thank you