A:Answer The LG - 24" Top-Control Built-In Smart Wifi-Enabled Dishwasher with Stainless Steel Tub, Quadwash, and 3rd Rack, Model # LDT5678ST can be installed with or without an air gap. Air gaps are the most effective means of preventing your drain from cross-contaminating your dishwasher with waste. If you want to protect your dishwasher from flooding with contaminated water, you need an air gap. Dishwasher air gaps are also required by plumbing codes in many locations. You will want to check your local building codes or contact your local building inspector to see if an air gap is required in your area. The air gap acts as a backflow prevention system and can become clogged after extensive use. Blockage in the air gap can prevent the dishwasher from draining, which will cause water to back up into the sink when the dishwasher is running. If you see water flowing from the air gap, there's most likely a clog...^IFV