Assessment of environmental sustainability indexes of water supply and sewage treatment companies listed on the BM&FBOVESPA

The measurement was performed by defining the boundaries of the system of each company with the sources of energy and materials that feed it. A system energy diagram was constructed and the flows were summarized in an aggregate diagram of the energy flows. From the inventory of energy and material inputs of the companies in 2013, the resources R, N, and F were inventoried in units, transformations, and eMergy/unit.

It has been found that consumers are paying, in seJ/J or seJ/R$, for the resources received from natural ecosystems when they buy products and services in cash. The calculation of accounting indicators in eMergy (EYR, ELR, and SI) and the ternary diagram in eMergy and their sustainability lines indicated the companies' positions in relation to environmental sustainability indicators. Investors of the BM&FBOVESPA acknowledge and perceive positive value in companies labeled as sustainable.

Between 2006 and 2015, the ESI obtained a performance index 131% higher than the Ibovespa index. Clients of the companies CASAN, COPASA, SABESP, and SANEPAR pay in their water and sewage treatment bills (average values in R$) for 72.5% of the total eMergy they receive. There is a disadvantageous relation between the biosphere and the water and sewage treatment systems operated by the assessed companies.