The Microbiology laboratory carries out bacterial testing on water from a range of sources including private dwellings, livestock farms, poultry farms, hotels, swimming pools, small businesses, and large food production companies. Advice on water testing, in addition to interpretation of results, is one of the many services we offer.
The method of testing involves membrane filtration and is applicable to waters from a wide range of sources including potable waters, pool waters and surface waters. The negative pressure membrane filtration method is used for the enumeration of coliforms, Escherichia coli and Enterococci, and the detection of Clostridium perfringens, sulphite reducing bacteria, Pseudomonas aeruginosa and other bacteria as may be necessary in various water samples. This method is based on the Health Protection Agency (HPA) Standard Method (W1), issued by the Standards Unit, Evaluations and Standards Laboratory in conjunction with the Regional Food, Water and Environmental Co-ordinators Forum.
The principle of the test utilises a known sample volume of water, which is drawn through a 47 mm diameter hydrophilic membrane filter under negative pressure. The 0.45 µm pore size of the membrane results in bacteria in the water being retained on the surface of the membrane. The membrane is then placed on agar growth medium and after the appropriate incubation period, a count is carried out of the microorganisms forming colonies on the membrane.
We offer a comprehensive bacterial analysis package which includes E. coli and coliform, faecal E. coli and enterococci, and total viable count at 22◦C and 37◦C. This package gives an excellent overall view of the water quality from a bacterial perspective. Advice and interpretation of results is part of the package we offer.
