Why microbiology sampling first for water then chemical sampling ?
It is not mandatory to collect water sample first for microbiology and then for chemical analysis.
But I observed most of pharmaceutical company, write the procedure for 1st micro sampling done.
And my senior also ask this question why do this?
Its so because we may sometime touch sampling bottle or any other non sterile part to the nozzle of the sampling point which may be the point for false results.
Chemical sampling is done irrespective of microbial sampling.
The practice which you cited is for cleaning validation of equipments, microbial followed by chemical.