The Federal Register, Part III, dated Thursday, 29 June 1989, 40 CFR Parts
141 and 142 states that heterotrophic bacteria may interfere with total
coliform analysis. Therefore, if the total coliform sample produces a turbid
culture in the absence of gas production, using the Multiple Tube
Fermentation (MTF) Technique, or an acid reaction, using the Presence-
absence (P-A) Coliform Test; or confluent growth or a colony number that is
"too numerous to count" using the Membranes Filter (MF) Technique, the
sample is invalid (unless total coliforms are detected, in which, case, the
sample is valid). The system must, within 24 hours of being notified to the
result, collect another sample from the same location as the original sample
and have it analyzed for total coliforms. In these cases, EPA recommends
using media that is less prone to interference from heterotrophic bacteria for
analyzing the replacement sample." The 24-hour time limit may be waived on
a case-by-case basis.
PREPARATION OF EQUIPMENT
a. Water Testing Kit, Bacteriological (see figure 3-2). The bacteriological
water testing kit is a standard item of table of organization and equipment (TOE) issued
to preventive medicine units and the preventive medicine section of the division medical
battalion. It has a portable incubator heated by direct current from a 6-, 12-, or 24-volt
battery; or it may be powered by 115-volt, 60-cycle or 230-volt, 50-cycle alternating
current. Adapters are provided for standard US or European wall outlets, battery
terminals, or vehicle cigarette lighter receptacles. A manual of instructions is issued
with the kit. It contains the following equipment:
(1). Funnel and filter-support assembly.
(2). Hand suction pump.
(3). Measuring cup.
Petri culture dishes.
Membrane filter disks.
Culture media or endo broth.
(10) Distilled water.