What is the minimum size of a fixture water supply pipe for a flush valve toilet?

The minimum size of a fixture water supply pipe for a flush valve toilet is indeed 1 inch. This size is necessary to ensure that the toilet receives an adequate flow of water during operation, allowing for efficient flushing. A flush valve toilet requires a larger volume of water quickly to function properly, and a 1-inch supply line is specifically designed to provide that high flow rate.

Using a pipe smaller than 1 inch can result in insufficient water supply, leading to weak flushes and potential performance issues. Additionally, plumbing codes often dictate this size to standardize installations and promote efficiency across various plumbing systems. The importance of maintaining a minimum pipe diameter cannot be overstated, as it directly impacts the performance and reliability of the plumbing fixture in question.