Standard Operating Procedure For Cleaning Of Overhead/U.G. Tank

by Pharmadocx Consultants

PURPOSE:  To ensure that the water storage area clean and free of contamination.

SCOPE: This procedure applies for the storage of water in a  clean overhead/U.G Tank

RESPONSIBILITY  : 1. Maintenance Supervisor

                               2. Maintenance Engineer


The plant is having two overhead tanks of 1000 liters and 500 liters capacity respectively. The plant also has an underground storage tank of 4000 liters capacity.

Total overhead storage facility is 1500 liters of water at any given time.

Overhead tanks and one underground tank are cleaned on the last working day of every second month. Thus it comes to 6 times in one Calendar Year.

However if the water in the tank gets infected by rodents, insects or any small creatures or by dust dirt etc. the tanks are cleaned under “emergency cleaning schedule” immediately.

The record for cleaning is kept in the register using the following format:

Overhead/underground tank cleaning register 
DateNature of CleaningCleaning Vehicle Time of commencementTime of completionCleaned byChecked byRemarks By Q.C.

Cleaning Procedure:

  1. All the tanks are emptied out and only one-inch water level is allowed to be there.
  2. Rent is drained out.Bottom and inner surface of the tanks are scrubs by scrubber and the residue/or left over dirt is manually removed.
  3. The adhered dirt is soaked with 2-3 buckets of water and again all the left over dirt is manually removed.
  4. The tanks are re-washed 3-4 times in the same manner till the outgoing waters show no colour/taste of potassium permanganate.
  5. All the taps and other water outlets are kept open in each sequence of water draining out and rinsing operation.
  6. Finally when the water is found absolutely normal no task, colour or smell of anything particularly KMN04.  The tanks are refilled and reuse is started.
  7. Bucket is filled with 10 liters of water and in it 50gms of potassium permanganate is dissolved.  This solution is then poured in the O.H./Underground Tank.  For the other tank the same procedure is followed.
  8. After pouring KMN04 solution all the tanks are filled with water by running the pump. The tanks are kept as such for overnight and next morning the outlets are opened and KMN04 solution is allowed to drain out intermittent scrubbing is done using wooden handle brass scrubbers.
  9. All the tanks are then refilled with water and then kept for two hours after that draining out is started with intermittent scrubbing.

    Emergency Cleaning Schedule:

    If the water gets contaminated in any overhead tanks due to rodents, insects, small birds, lizard, dirt & dust etc., the following emergency cleaning is done immediately.

    1. The outlet of the infected/contaminated tanks is served out from the main outlets channel so that no water can go to the line from the same tank.
    2. The debris is taken out.
    3. Cleaning as per general procedure No. 1 and 2 is done.
    4. The tank is then washed with 5% IPA v/v solution in the ratio of 20% of the total tank capacity i.e. in case of 500 liters, tank 1000 liters of the above solution.
    5. The solution is drained out and further 50% (i.e. 50 liters in case of 500 liters tanks) of the same solution is added and scrubbed thoroughly.
    6. The tank is then rinsed with 100 liters of water two times.
    7. Then onwards the general cleaning procedure then 4 to 7 are followed.
    8. The tanks are then is connected back to the main line and washed with water.
    9. The tank is then opened for reuse.
    10. Water sample is drawn and given to QA for testing and clearances.

    NOTE: Potability test of water done twice a year including bacteriological test like total bacterial count, salmonella, E. Coli etc. as per ISI. Bacterial quality is checked once in three months in our own laboratory.

    Author: (GM Production)Checked by: (QA Manager)Authorised by: (Director Technical)
    Date:Date :Date :

                            (Review date on or before 12 months from date of authorization)

    Written by Anmol Singh

    Anmol Singh Completed his Bachelors in Field of Mechanical and Automation Engineering. He has over 2 Years of experience in field of Pharmaceuticals, Medical Devices, Cosmetics Manufacturing.

    11 June 2023

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