Merck’s Membrane filtration technique complies with international standard such as standard methods for Examination of Water and Waste water, US EPA, and EU testing procedures for drinking water or other filtration testing it’s simple: the test sample is filtered through a microporous membrane, allowing the retention of microbial contamination on top of the membrane. Rinsing removes residues that might inhibit the growth of microorganisms. Once the sample is filtered, nutrient medium is added to promote growth of microorganisms for recovery. For testing non-filterable samples, Merck offers a large selection of culture media of the high quality.