Ground water and lake temperatures are often much lower than air dewpoints, which can result in condensation on the outside of the pipes, valves and controls in the water plant. Providing dry air to the plant prevents the condensation that leads to mold and fungus growth, as well as rusting the valves and controls. The cost of the dehumidifier is very modest compared to the cost of painting pipes and periodical replacement of controls and valves. Additionally, the sanitary benefits of eliminating fungus and bacteria have increased in importance as consumers become more sensitive to water quality issues.
When power plants are idled for maintenance or because of excess generator capacity, dehumidifiers are installed to blow dry air through both the steam side and generator windings. This costs less and is safer than blanketing with nitrogen, and is far more effective than either wet layup with corrosion inhibitors or preservation in grease. Dry air layup is very simple, and the plant can go back on-line in a matter of hours rather than weeks.