I perform quarterly testing on hand sinks in the facility. Normally I see a range of 0-40 APC (our limit is 500 but I prefer to see it under 100). I recently had a sink fail with a TNTC result (too numerous to count) which typically indicates a reading of over 1,000,000. I removed the aerator and tested the water, and it came back 17. Then I sanitized and replaced the aerator and it came back 57. Upon sanitizing the aerator again pulling the sample I got another TNTC result two times in a row. Moving further into the investigation, I pulled another set of samples with the aerator, without the aerator and then directly from the water source under the sink. The results are as follows:
With aerator - 5,400
Without aerator - 485
Water Source - 760
As you can see there are some inconsistencies but the problem is still identified - water directly from the wall is contaminated.
Aside of replacing the aerator and taking the sink out of service, what would your next steps be? I am going to have to communicate with maintenance on how to address this issue and I am trying to get an idea of what resources other facilities use to take care of issues such as this one. Thank you!