A closed loop contaminant control system for an evaporative water purification process at an oil recovery facility includes an evaporator having a water inlet, a distilled water discharge, and an oil and brine water discharge. A sump in the evaporator is divided by an oil skimming weir into a main sump and a blowdown sump, with the oil and brine water discharge located proximate the blowdown sump and the steam discharge located above the oil and brine discharge. A distillate tank receives distilled water from the evaporator and discharges the distilled water. The distillate tank has a level controller, other controllers provided for the system include a distilled water flow meter, a blowdown flow meter, a cycle controller, a total flow controller, a hardness controller, and a silica controller.