The BLANCO AIR GAP is an effective way to prevent backflow into your dishwasher. If your sink becomes clogged, the hose leading to your drain will to start to push water back into your appliances, including your dishwasher. Without an air gap your dishwasher can flood with contaminated or waste water. Often, air gaps are required by plumbing codes and the BLANCO AIR GAP satisfies these plumbing regulations.