Air compressor oil and water separators are designed to remove lubricants (or oil) from condensation within your system (water). The oil/water separators are normally installed downstream of the compressor tanks. In a compressor, the condensation within the lines becomes contaminated by the oil. This creates an issue as the water condensation needs to be expelled into the sewage system but can't with the oil present. This is where an air compressor oil/water separator comes into play separating the two and enabling the condensation to be expelled without the risk of contamination.