Feedwaters to a refinery are usually treated before being used in various processes. The type of treatment depends on the quality of the source water and its end use in the refinery. Turbidity, sediment, and hardness are examples of source water characteristics that may require treatment.

In the boiler industry, high purity feedwater is essential to ensure proper operation of steam generation systems. High purity water reduces the use of boiler chemicals due to the frequent reduction in blowdown output required (reduction of blowdown frequency by up to 10 times).