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