The pharmaceutical industry is a highly water-dependent economic sector and requires different degrees of water purity. The study presents an overview of the current water quality requirements, as well as limitations and safety considerations for water re-use in pharmaceutical manufacturing. Several principles for implementing circular economy elements into pharmaceutical wastewater treatment procedures are described: the use of recovered solvents as an easily degradable carbon source for the denitrification process, the use of phosphorus-containing wastewater as a nutrient source for activated sludge microorganisms, the use of inorganic acids and bases for pH control in wastewater treatment processes, and the use of Al3+ containing wastewater as a coagulant. The case study indicates that specific wastewater streams can be reused as secondary materials if the chemical composition of wastewater from pharmaceutical batch processing is well constrained and separate collection is ensured.