Further examination of Pitt's definition (2004) indicates that
only the first two properties are substantive; the third one is given
by operational and resource limitations, which could be overcome.
Examination of information in Table 2 indicates that caffeine and
carbamazepine more or less meet the substantive requirements
and could be recommended for further studies of contamination by
wastewater. Both are conservative, which distinguishes them from
the majority of indicators listed in Tables 1 and 2 (e.g. appearance,
odour, temperature, conductivity, microbiological indicators,
different forms of phosphorus and nitrogen, etc.). However, combinations
of non-conservative parameters may improve the feasibility
of detecting wastewater contamination in general (Juanico
et al., 1990).