Operation Manual

18
Assessment of the oil test:
The oil test should be carried out by the same person each time as the colour
change is a subjective judgement. Once or twice a year we recommend that a litre
sample of filtrate be sent in a glass bottle (not plastic!) to your local water-
company-laboratory for testing. This then controls the judgement of the sampler
and gives confidence to the environmental officers who can check your effluent.