There is a much greater flexibility in the way that the spread plate technique can be used. The medium has not rigidly been laid down and there are seven or eight different media are in widespread use. Paralleling this, there is a flexibility in the temperatures and incubating times used. Common temperatures used include 8 to 10, 20 to 22, 25 to 28, 30, 35 to 37 and 45 oC. The selected temperature reacts directly on the incubation times, particularly at the lower end of the scale. At temperatures below 25oC, a prolonged incubation allows more time for the bacteria to grow. For example, at 8 to 10oC, bacteria can take up to six weeks or longer before forming a visible and countable colony and so the plates should be incubated to the longest term. In requesting a TPC, questions should be raised as to the medium, temperatures and times that are going to be used. one of the frustrations in requesting bacterial counting of a water sample is the long delay before the numbers return, perhaps long after the treatments have been implemented. A number of new techniques are being examined to cut down this response time. These include particle counting, epiflorescent microscopy sophisticated staining and biochemical methods which search individual enzymes or marker chemicals.