Chemical injection processes are used ahead of distillation systems to eliminate chlorine, chloramines and ammonia from feedwater. Injection systems consist of chemical tanks, injection pumps and pump controls.

Sodium bisulfite systems are used to create a chemical reaction to eliminate chlorine. However, sodium bisulfite cannot serve as a substitute for a carbon filter because it has no effect on organics. Sodium bisulfite systems are appropriate for water sources with organics that cause no foaming in the evaporation process. As with water softening, sodium bisulfite systems break down chloramines but still leave ammonium ions in the feedwater, requiring further treatment.

Sodium hypochlorite chemical injection systems are also used ahead of distillation systems to destroy chloramines, a process known as break-point chlorination. Injecting enough sodium bisulfite in the presence of chlorine converts the chlorine to chlorides, but there must be sufficient contact time between the chlorine and sodium bisulfite. This is accomplished by adding a tank in the system. This process leaves a small amount of chlorine in the feedwater that needs to be removed by a carbon filter.