I developed a cleaning method for our production vessels. Our production staff did a cleaning of one of our vessels via the method, a 2000 gallon pressure vessel. I collected an initial rinse sample, then the vessel was cleaned per the method with an alkali cleaner, then a final rinseate sample collected. I had the samples tested for HPC, Total coliform, and E. Coli. The initial rinseate sample came back positive for Total coliform (little scary), and was > 5,700 cfu for HPC. The final rinseate sample came back negative for E. coli and Total coliforms and 28 cfu for HPC. I would have done a swab (think this would have been better than rinseate), but to get into the kettle to do a proper one would require a Confined Space training and permit, which none of us have. Also, the rinseate was collected after use of the alkali cleaner but before use if the sanitizer.
1) Is the testing I'm doing valid? Is there another way that's better?
2) Should the final rinseate sample been collected after the sanitizer? The method does call for a sanitizer to be applied after use of the cleaner.
3) Am I using the right test to validate?
4) How many cleanings do I need to do and samples I need to collect to prove I have validated?
5) Is the final rinseate reading OK? Do I need a final reading of 0 cfu?
Any input would be greatly appreciated.