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.