Reject, backwash, and concentrate wastewaters from reverse osmosis processes may be discharged to a water of the state subject to the requirements under s. NR 811.85 (1) (b). Chemical cleaning waste shall not be discharged to a water of the state. An equalization tank of sufficient size to allow discharge over at least a 24-hour period shall be provided for a surface water discharge. The department may approve a smaller tank or no equalization if the waterworks facility demonstrates to the department that reduced equalization is unnecessary to prevent toxicity to aquatic life.
Wis. Admin. Code Department of Natural Resources NR 811.855