Wis. Admin. Code NR § 810.20
Water suppliers shall notify the department of any operational changes involving adjustment of chemical addition, filtration, or other operational parameters that may impact the quality of water produced. Temporary changes to manage water quality variations do not require department approval provided the operation remains within prior approved target ranges. Use of alternate chemicals, adjustment outside prescribed treatment ranges previously approved by the department, or permanent operational changes may not be made unless approved by the department prior to the change.
Wis. Admin. Code Department of Natural Resources § NR 810.20
Modifications of chemical dosages or changes in chemicals may significantly alter the corrosion characteristics of the water as well as impart odors and tastes. Careful consideration of the impact to water chemistry should be given prior to adjusting chemical treatment.