What is the minimum diameter of a floor drain waste outlet?

The minimum diameter of a floor drain waste outlet is 2 inches because this size is generally required to ensure adequate capacity for draining wastewater effectively. A 2-inch diameter outlet can handle typical flow rates from appliances or bathroom fixtures and is designed to minimize the risk of clogging while allowing for proper drainage and venting.

In plumbing standards and codes, adhering to this minimum diameter helps in maintaining clear and efficient drainage systems, preventing water backing up and potential overflow issues. It ensures that the drainage system can handle the anticipated volume of water from various sources, enhancing both functionality and safety in a residential plumbing design. Smaller outlets could lead to insufficient drainage, particularly during heavy use, leading to issues like water pooling or flooding.