Administrations should ensure that the equipment is installed
in a manner which facilitates the collection of samples. Sampling
should be carried out in a manner and at a frequency which is representative
of effluent quality. Sampling frequency should take account of the
residence time of the influent in the equipment. A minimum of 40 effluent
samples should be collected to permit a statistical analysis of the
data (geometric mean, maximum, minimum, variance, etc,). An adequate
number of influent samples should be collected to ensure compliance
with item 1. Any disinfectant residual in samples should be neutralized
when the sample is collected to prevent unrealistic bacteria kill
or chemical oxidation of organic matter by the disinfectant brought
about by artificially extended contact times.