Traditional cleaning works by dissolving corrosion deposits and metal oxides. This creates heavy metal discharge far above required discharge limits. Virtually all the cleaners that usefully clean are based on chemistry that will violate discharge rules. It is impossible to remove corrosion deposits and mill scale formed during pipework and equipment fabrication and not dissolve metal ions. Closed loop cleaning is believed to be the largest source of heavy metals such as copper, zinc, lead, and molybdenum to the sewage system. It is a significant source of phosphorus discharge. Heavy metals and phosphorus discharges are damaging to the environment. Even when captured by a sewage treatment plant, they cause sludge disposal problems. Closed loop cleaning typically creates ten times the volume of the system being cleaned in discharge water. Approximately 0.5% of all sewage is the result of closed loop cleaning.