Abstract : Carbon dioxide treatment for controlling and removing scale deposits in potable water systems has been investigated for potential application at Army installations. Scaling of water treatment systems is costly in terms of severe headloss and reduced carrying capacity of pipes, loss of heat transfer capacity in water heating systems, high operating costs due to inefficiencies, downtime and maintenance, and operational safety hazards. Conventional treatments for scale removal and control include mechanical and chemical methods. These methods are expensive and often ineffective; in addition, some chemical additives are unsafe, requiring special handling techniques and evacuation of building occupants during treatment. The Illinois State Water Survey has successfully field-tested a carbon dioxide treatment system. Treatment with controlled levels of carbon dioxide removed scale deposits safely and effectively; subsequent treatment kept the test pipes relatively scale-free while in service. However, one drawback is that overtreating a water system can result in corrosion due to dissolution of the scale and the protective coating on pipes.