_________________________ is the minimum size for a residential garage drain?

The minimum size for a residential garage drain is 3 inches. This size is specified to ensure that the drain can adequately handle the typical water flow and potential debris from vehicles and washing activities that occur in a garage setting. A 3-inch drain allows for effective drainage, helping to prevent water accumulation and ensuring that water flows freely away from the garage area. Proper drainage is crucial to avoid water pooling, which could lead to structural damage or create a breeding ground for pests.

Other sizes, while they may be suitable in some contexts, do not meet the minimum requirement set forth in the plumbing code for the effective function of a garage drain. For instance, a 2-inch drain may not have the capacity to handle the larger volumes of water associated with a garage environment, while larger sizes like 4 or 5 inches could be unnecessarily expensive or impractical for typical residential applications.