1.1 ,This test method describes a procedure that can be used in the field or in a laboratory to quantify culturable, viable aerobic microorganisms present as contaminants in liquid fuels, including those blended with synthesized hydrocarbons or biofuels, with kinematic viscosities (at 40 ,°,C) of ≤,24 mm² s^-1 and heavy and residual fuels with kinematic viscosities (at 40 ,°,C) of ≤,700 mm² s^-1 and in fuel-associated water.