Polyethylene encasement (PE) is a coating method that consists of a loose wrap of thin plastic around ductile iron piping (DIP), that is typically held in place with PVC tape. It has become the primary means of corrosion control on DIP water and wastewater piping even though no large scale independent studies have been performed to document how often the thin plastic is damaged. Damage to the PE exposes the DIP to direct soil contact and corrosion can occur. The frequency of these exposed anodic (corroding) areas on polyethylene encased DIP has also never been compared to the frequency of anodic areas on uncoated DIP. Uncoated DIP is DIP that that has the 2 to 3 mils thick factory applied black asphaltic paint applied to it. The asphaltic paint is water permeable and provides no significant reduction in corrosion activity on DIP. This research project evaluated cell-to-cell potential data on 89,275 feet of uncoated DIP and 51,609 feet of polyethylene encased DIP. Cell-to-cell potential measurements are the only way to accurately detect areas of corrosion on unbonded DIP.