Which size is used for a water closet supply line with flushometer?

Which size is used for a water closet supply line with flushometer?

• A. 1/2 inch
• B. 1 inch
• C. 3/4 inch
• D. 1 1/4 inch

Answer: (B)

A flushometer-equipped water closet needs a supply line sized to deliver a strong, immediate flow to the valve. The 1-inch line is the standard size because it provides enough flow (GPM) to meet the flushometer’s demand without significant pressure drop. Smaller lines, like 1/2 inch or 3/4 inch, can restrict flow and lead to weak flushes or slow refills. A 1 1/4 inch line is larger than typically needed for a single toilet and is not common for standard commercial fixtures. So, using a 1-inch supply line ensures reliable, full performance of the flushometer.

A flushometer-equipped water closet needs a supply line sized to deliver a strong, immediate flow to the valve. The 1-inch line is the standard size because it provides enough flow (GPM) to meet the flushometer’s demand without significant pressure drop. Smaller lines, like 1/2 inch or 3/4 inch, can restrict flow and lead to weak flushes or slow refills. A 1 1/4 inch line is larger than typically needed for a single toilet and is not common for standard commercial fixtures. So, using a 1-inch supply line ensures reliable, full performance of the flushometer.