Municipal Sewage is highly contaminated wastewater that contains several types of pollutants that including heavy metals, total organic carbon, grease and oil, nutrients, total suspended solids, chemical oxygen demand (COD), biochemical oxygen demand (BOD) and microbial contaminants. The chemical composition of sewage is very complex and variable, depending on different sources. Nowadays, microplastics and other emerging contaminants are also found in sewage. The improper disposal of untreated or partially treated sewage may cause soil and water pollution. The toxic contaminants present in sewage affect aquatic life and human health. The conventional sewage treatment methods include filtration, coagulation, flocculation, adsorption and disinfection. Membrane technology, advanced oxidation processes (AOP), activated carbon method, membrane bioreactor (MBR) and activated sludge process (ASP) are the advanced treatment methods. This chapter includes characterisation of sewage, various treatment methods as well as its impact on human health, and environment.