New watermain bacteriological samples test procedures
New watermain bacteriological samples test procedures
(OP)
I am trying to find documentation/clarification on bacteriological testing requirements.
According to AWWA Standards, C651-99, Section 5.1, two consecutive setsof acceptable bacteriological samples are required. I am trying to clarify the requirements on the second day samples. It is my understanding that the second day samples are to be taken from the new water main without any flushing of the main - only flushing prior to
first day samples. Some Chlorination contractors insist that second day samples are to be taken after another flushing of the water main with supply source.
Is there clear documentation on acceptable second day testing procedure.
According to AWWA Standards, C651-99, Section 5.1, two consecutive setsof acceptable bacteriological samples are required. I am trying to clarify the requirements on the second day samples. It is my understanding that the second day samples are to be taken from the new water main without any flushing of the main - only flushing prior to
first day samples. Some Chlorination contractors insist that second day samples are to be taken after another flushing of the water main with supply source.
Is there clear documentation on acceptable second day testing procedure.





RE: New watermain bacteriological samples test procedures
How the main is disinfected is between the owner and their engineer. AWWA is a guidline for this. You should be upfront with the contractor prior to starting construction so that he knows the deal in advance.
Hope this helped.
Bob Yurick PE
RE: New watermain bacteriological samples test procedures
Jim
RE: New watermain bacteriological samples test procedures
Bob is right on, the first test is after flushing, and the flushing is actually intended to remove the initial high chlorine levels used to disinfect the pipe. The second sample is a check for what exists in the background of the pipe. Flushing again defeats the purpose, as your testing water from another source, not whats resident in the main you just installed. This check indicates wether the initial cleaning (and or pigging) was sufficient in removal, and if the water itself has sufficient residual to eliminate any background bacterial issues.