An oil interceptor works in almost exactly the same way as a grease trap. However, instead of capturing kitchen fats, it captures the oil, petrol and diesel that finds its way onto the floors of garages, car parks, transport depots and other places where vehicles are serviced or parked.

When it rains on outdoor surfaces, or if any surface is washed down with water, the water and the contaminant are washed into the oil interceptor. The oil interceptor allows the mixture to settle making it easier to separate the two and prevent the oil, petrol or diesel entering the environment.