His main fields of research are membrane processes for wastewater treatment, desalination of saline and hypersaline brines, reclamation of impaired water for potable reuse, and energy from water and wastewater. Additional field of his research focuses on life cycle assessment and techno-economical evaluation these processes and the development of decision support tools for selection and optimization of treatment processes. Dr. Cath is the principal investigator on many research projects focusing on the integration of membrane contactor processes in seawater and brackish water desalination, in domestic and industrial wastewater treatment, and in life support systems. Dr. Cath is also the director of the Advanced Water Technology Center (AQWATEC) at Colorado School of Mines.