Investigation of source water quality is a key factor in selecting technologies to deal with certain water contaminants. Risk assessment and risk management are major tasks for drinking water systems engineers, managers and the regulatory agencies. Development of contingency plans are necessary to water systems, and having a multi barrier system is an approach started to become familiar to avoid any potential public exposure to water contamination that could have a serious impact on human health. Harmful Algal Blooms (HABs) are becoming a continuous challenge to the ecosystem and human health due to climate change, discharged nutrients from agriculture activities, improperly treated or untreated sewage effluents and others. Harmful Algal Blooms (HABs) are becoming a continuous challenge to the ecosystem and human health due to climate change, discharged nutrients from agriculture activities, improperly treated or untreated sewage effluents and others. The selection of certain technologies to deal with such challenge must take into consideration their impact on the sustainability of the water system. The successful applications of ozone and ozone based advanced oxidation process (AOP) gained major interest in mitigating challenges associated with cyanotoxins. (C) 2016 Elsevier B.V. All rights reserved.