Compressed air systems are sometimes called the "4th Utility" due to their presence in almost all industrial processes and facilities. As US water consumption continues to increase, compressed air systems provide an opportunity for energy managers to reduce associated cooling water consumption and costs. In this white paper, we focus on the opportunity to reduce the water consumption of compressed air systems. Understanding the costs and the alternative types of cooling systems is an important first step. This white paper provides background on US water consumption in both the public and industrial sectors; it provides detail on industrial water consumption -- including industrial cooling water – and its associated costs; it also details six different types of cooling systems available.