A wholesale/retail model delivers drinking water to over 5 million residents in metropolitan Melbourne (Australia). Water Safety Plans were implemented in 1999 ahead of being regulatory mandated in 2003. With over 20 years of WSP application, this collaborative paper by the wholesaler and retailer utilities presents practical examples of drinking water quality risk management in challenging operational environments, highlighting lessons learnt, improvements made and outcomes achieved. Melbourne’s supply comprises multiple sources, necessitating different tailored treatment configurations. Source waters range from open catchment with multiple treatment barriers, to protected catchment source waters requiring solely disinfection treatment (unfiltered) with gravity driven supply. Potable supply is a combination of unfiltered, filtered, desalinated and blended supplies. This makes for diversity in case studies brought to this paper, and a range of lessons likely to be of interest to the global WSP community. The Melbourne utility experience highlights the importance of developing and continually improving control measures for ongoing (adaptive) risk reduction. A robust emergency management plan is also fundamental to ensure preparedness for complex and unpredictable events. Furthermore, leveraging learnings from audits and incidents has been valuable for process improvement. WSP implementation has also facilitated timely communication with consumers and other stakeholders.