Final answer:
The minimum size for toilet drain piping is typically a 4-inch pipe, following standard building codes and the need for efficient waste disposal.
Step-by-step explanation:
When considering the minimum size for toilet drain piping, it is important to adhere to local building codes and regulations which typically require a minimum of a 4-inch pipe. This size is sufficient to handle the flow and avoid clogs in a residential installation. In some commercial settings, pipes may be larger due to higher usage rates, but a 4-inch pipe is standard for home installations. The Table 7.15 Comparing Pipes: Economies of Scale in the Chemical Industry and descriptions of pipe sizes in various applications, including scenarios like the Thames' Great Stink, indicate the importance of proper waste disposal and the related health and environmental considerations.