This paper proposes a method to determine harmonic pollution of consumers connected to single-phase low voltage distribution system. Today, the power quality of the system is greatly affected due to the penetration of non-linear loads. As per the IEEE standard 519-2014, both utility and consumers are responsible for reducing the harmonic pollution. This necessitates the quantification of harmonic contribution of individual consumers. The proposed method defines harmonic distortion indices for current and voltage separating consumer harmonic contribution at the point of common coupling (PCC). These indices are used to determine non-fundamental apparent power associated with each consumer connected to the PCC. Simulation results point to the effectiveness of this method in separating the harmonic contribution of consumer and utility. Experimental investigations are also carried out with several linear and non-linear loads comparing the performance of the method with the power definitions mentioned in IEEE standard 1459-2010.