This updated Guide offers comprehensive guidance on designing and operating pharmaceutical water storage and distribution systems that utilize ozone for sanitization. It outlines key principles for implementing an effective sanitization approach. Using ozone as the primary sanitizing agent in a pharmaceutical water distribution system offers a wide range of operating and cost advantages. Their significance varies depending upon the site and project. Like all sanitization methods, ozone technology imposes specific requirements on system design and operation. As with any system design, it is the responsibility of the owner and the design team to evaluate ozone’s applicability and compatibility with processes and APIs. This Guide provides design guidance to assist in this evaluation and decision. The key advantages of Ozone Sanitization discussed in this Second Edition include: Improved Water Quality Reliability Higher Productivity Capital Equipment Savings Safety Pipe Insulation Reduced Energy Costs Reduced Carbon Footprint Advantages over Chemical Sanitization Reduced System Downtime Ease of Frequent Use Reduced Excursions and Related Cost Reduced Water Consumption Reduced Chemical Disposal Costs This Second Edition of the ISPE Good Practice Guide: Ozone Sanitization of Pharmaceutical Water Storage and Distribution Systems describes established design methodologies. Drawing from their experience, the expert team of authors share best practices to assist in expanding use of ozone sanitization based on knowledge of its principles and benefits.