Appendix B

Table B.1. Atypical bacteria data generated by the studied utilities from 1997 through 1999

	Number of positive samples			Percentage of total number of samples			Average colony counts, cfu/100 mL *
	1997	1998	1999	1997	1998	1999	1997						1998						1999
								Percentiles						Percentiles						Percentiles
							Min	C10	C50	C90	Max	Mean	Min	C10	C50	C90	Max	Mean	Min	C10	C50	C90	Max	Mean
Nonproblematic utilities	15	11	3 **	7.3	5.8	1.6 **	1	1	2	200	200	2	1	1	15	200	200	6	3	3	35 **	56	56	31 **
Problematic utilities	23	63	48	11.9	20.6	11.7	1	1	13	200	200	12	1	1	10	200	200	26	1	1	6	165	200	24

* The determination limit was indicated by the QME accredited laboratories as > 200 cfu/100 mL; so this value has been considered herein as the maximum.

** Data obviously not representative because of too small sample size (n=3).

Table B.2. Distribution water boiling notices issued by the studied utilities from 1996 through 2001