6418.1 A swimming pool or spa shall be deemed contaminated when one (1) of the following conditions exists:

1. (a) More than one (1) ten milliliter (10 ml) portion of a sample shows a positive test for coliform organisms when multitube fermentation technique is used; or more than one (1) coliform per fifty milliliters (50 ml) when the membrane filter test is used; or
2. (b) Two (2) consecutive samples show a positive test for coliform organisms in any ten milliliter (10 ml) portion of a sample when the multitube fermentation technique is used or more than one (1) coliform per fifty milliliters (50 ml) when the membrane filter test is used; or
3. (c) Two (2) of any ten (10) consecutive samples show a positive test for coliform organisms in any of the ten milliliter (10 ml) portions of a sample when the multitube fermentation technique is used or more than one (1) coliform per fifty milliliters (50 ml) when the membrane filter test is used.

SOURCE: Final Rulemaking published at 55 DCR 012845 (December 26, 2008).