Changes

* '''Membrane filtration'''. In order to overcome the problem of small sample volumes usually associated with direct count methods, larger volumes of water samples can be filtered across a membrane that has pores that are too small for bacteria to pass through (usually 0.3 microns). The membrane is then aseptically transferred to a flat dish containing the culture medium, where the bacteria are grown.

{|style="border: 1px solid #63B8FF; text-align: center; background-color: #ffffff"

|}