Sterile nutrient media (Postgate) are used for quantitative control of SRB, which are, in some cases, one of the main causes of corrosion. This method is based on successive (from one flask to another) dilution of potentially contaminated field water in several flasks containing test media (Postgate). The quantity of SRB in field water is determined by the quantity of "blackened" media flasks. The media are supplied in 10 ml flasks.