Corrosion Control If sequestration of iron and manganese is practiced, the chlorine residual in the water system should always be maintained at or above: Tags: Certification Exam Prep, Chlorine Residual, Distribution System, Iron, Manganese, Sequestration, Water Treatment Read more articles Previous PostWater Treatment and Distribution System Next PostWater Treatment and Distribution System You Might Also Like Texas Water License Exam Prep 2 of 2 February 19, 2019 State Exam Information | California Distribution Operator Certification June 12, 2018 Water Treatment | Well Construction April 17, 2018 Post author: Post published:January 11, 2017 Post category:Certification Exams / Distribution / Water Treatment