Transition towards circular-economy model is a must to sustain the planet resources. Under circular economy model wastewater is transformed from a waste into a resource. Therefore, a comprehensive circular economy index; the Circonomics Index, is proposed to measure circularity of wastewater industry. The component indicators of the index are linked directly to the three Rs; reduce, reuse and recycle, of circular economy. The novelty of the proposed Index is that it uses objectively constructed weights that reflect the environmental benefits of the treatment process, and the index captures the reuse and recycling efficiency of an WWTP, which reflect the specific nature of wastewater. The findings show that treatment technology is a major factor in determining the production efficiency, reuse rate and recycling performance of a WWTP. The results of using the Circonomics Index have profound implication for policy makers to speed up the process of moving to a circular economy.