Direct potable water reuse (DPR), the injection of highly purified wastewater into drinking water systems, is among the newest, and most controversial, methods for augmenting water supplies. DPR is garnering increasing interest, but does not come without risks. This paper examines the notion that emerging regulation of DPR may lack sufficient attention to a particular class of risks: catastrophic risks with low probabilities of occurrence, but high consequences. It may be instructive for proponents of DPR that such consequences have materialized in other industries, with damage to human welfare and to the industries themselves. We develop brief histories of risk regulation from the aviation, offshore oil and nuclear industries, drawing out relevant lessons for the emerging DPR field. We argue that proponents of DPR could benefit from proactively developing a safety culture in DPR utilities and establishing an effective industrywide auditing organization that investigates unanticipated system failures. Developing independent oversight for DPR operation could ensure that stringent quality and management requirements are set and enforced, and that any system failures or "near misses" are investigated and adequately responded to.