This paper presents empirical equations for the evaluation of advective flow rates through composite liners, i.e. liners comprising a geomembrane and a low-permeability soil layer. The advective flow is due to defects in the geomembrane and depends on contact conditions between the geomembrane and the soil layer. Three types of defects (circular defects, defects of infinite length, and damaged wrinkles) and three types of contact conditions (excellent, good, and poor) are considered. The methodology for developing the empirical equations consists of selecting a mathematical expression for the empirical equations and selecting values for the unknowns of the empirical equations such that flow rates calculated using the empirical equations are as close as possible to flow rates rigorously calculated using existing analytical solutions. This was achieved by conducting numerical calculations for more than 120,000 cases defined by a wide range of values of the parameters (contact conditions, defect type and size, soil layer thickness and hydraulic conductivity, and hydraulic head). As the empirical equations are much simpler than the analytical solutions, they provide design engineers with a practical tool for evaluating flow rates through composite liners.