A mixed fluid separator apparatus includes an overload protection chamber that prevents a large and sudden influx of oil from fouling a coalescing separator. To prevent sudden influx of a large concentration of oil from overwhelming the coalescing separator, a separate overload protection chamber is connected to a main coalescing separator apparatus. The overload protection chamber includes a water drain (majority water with some oil) to the main coalescing separator apparatus and an oil overflow (majority oil with some water) to drain excess oil when necessary to prevent overfilling of the coalescing separator apparatus. The overload protection chamber functions to rapidly separate and remove heavy concentrations of oil, protecting the main coalescing separator apparatus.