AUTHORITY: Implementing Section 17 and authorized by Section 27 of the Illinois Environmental Protection Act [415 ILCS 5/17 and 27].POLLUTION CONTROL BOARD
a) A minimum free chlorine residual of 0.5 mg/L or a minimum combined chlorine residual of 1.0 mg/L must be maintained in all active parts of the distribution system at all times.
b) Community water supplies must monitor chlorine residual to determine the amount and type of residuals existing at different points in the distribution system.
c) Community water supplies must not mix water sources with free chlorine and combined chlorine residual.