What is the minimum size for a residential garage drain?

The minimum size for a residential garage drain is typically 3 inches in diameter. This size is considered adequate for efficiently handling the volume of water that might drain from the garage, including rainwater, melting snow, and any spills that may occur. A drain of this size can effectively minimize the risk of clogging while ensuring proper drainage, which is important for maintaining a dry and safe garage environment. Smaller drains may not provide sufficient capacity for the potential water flow, leading to drainage issues and possible flooding in the garage area. Therefore, a 3-inch drain is both practical and compliant with most plumbing codes for residential garage applications.