A. Your question covers a number of issues and misconceptions regarding dishwasher drain lines. Let's take them one at a time: • Most people have seen a dishwasher airgap. It appears as a small chrome cylinder, commonly found on the back rim of a kitchen sink. It is what plumbers call an anti-backflow device, because it prevents sewage from flowing back into the dishwasher. Your buyers' home inspector was correct in recommending that an airgap be installed. Alternative devices are available, but airgaps are specified in the plumbing code because they are the most reliable in all circumstances. It should be noted, however, that airgaps are not required in all states.
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