"Proponents of privatization consistently argue that it saves costs due to competitive pressures private providers face to be more efficient. Over the last four decades there has been considerable experimentation with privatization. Results are inconsistent. Some cases find savings; others do not. To get beyond the “battle of the case studies” my colleagues and I conducted a meta-analysis of all published studies on water distribution. A comprehensive scientific analysis shows the value of a careful review of theory and empirical evidence in making policy choices. Our analysis found no empirical support for cost savings."
By Mildred E. Warner
You can read the entire article here or download it in PDF here
Also well worth checking out is Reclaiming Public Water a groundbreaking book on how reformed public water services can achieve the goal of delivering water for all. Downloadable by chapter.