SOP on Microbial Testing of Drain Water

The Purpose of this SOP is To lay down the procedure for Microbial testing of drain water in the production area of the Pharmaceutical Manufacturing Site.

This SOP is applicable to describe the procedure of Drain monitoring Microbial Contamination for Production area and microbiology lab at of Pharmaceutical Manufacturing Site.


All drains in the production area shall be checked to monitor the effectiveness of cleaning and disinfecting agents once a month.
Sample 100 ml of drain water from each drain and collect it in a sterile glass container with the help of previously sterilized pipette.
 Following tests shall be performed on the drain water collected:

a) Total Microbial Count.
b) Absence of Pathogens.

 Filter the sampled drain water through 0.45 membrane filter.
For Phenolic disinfectants, dilution of drain water with sterile distilled water and filtration through 0.45 micron is sufficient. However, whenever other types of disinfectants.
Wash the filter paper 2 times with sterile Normal Saline 50 ml 1st time and 50 ml Second.
Inoculate the filter paper in 100 ml of Normal Saline.
Shake thoroughly (so that the contents of filter paper comes in Normal Saline).
Perform the Total Microbial Count and test for absence of Pathogens as per the standard.

Count and record the results in Drain Water (Microbiological Testing) Record.
Necessary feedback shall be given to Production for corrective action if required.

Frequency: Monthly

Acceptance Criteria:

For Bacteria 1000 CFU/ plate

For Fungi 100 CFU/Plate


Training is as per Training SOP

Annexure :

Annexure I: Microbial Testing of Drain water Logbook

Annexure II: Microbial Testing of Drain Water Report

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