Many factors may significantly affect coliform
bacteria detection by MTF, especially during the presumptive
phase. Interference by high numbers of noncoliform
bacteria (Seidler et al., 1981; Evans et al.,
1981; Means and Olson, 1981), as well as the inhibitory
nature of the media (McFeters et al., 1982), have been
identified as factors contributing to underestimates of
coliform abundance. The MTF technique lacks precision
in qualitative and quantitative terms. The time
required to obtain results is higher than with the
membrane filter technique that has replaced the MTF
technique in many instances for the systematic examination
of drinking water. However, this technique
remains useful, especially when the conditions do not
allow the use of the membrane filter technique, such as
turbid or colored waters.