The supply line size for a water closet with a flushometer is which of the following?

The supply line size for a water closet with a flushometer is which of the following?

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

Answer: (D)

When a water closet uses a flushometer, the valve delivers a rapid, high-volume surge of water to flush the bowl. That requires a supply line large enough to carry enough water without dropping pressure at the moment of flush. A 1-inch line provides the needed flow and helps ensure the flushometer can open fully and deliver the intended gallons per flush, even if there’s some pressure loss along the run. Smaller lines, like 1/2 inch or 3/4 inch, would restrict flow and could weaken the flush or cause the valve to operate inconsistently. Conversely, a much larger line isn’t typically necessary for standard installations. So, the 1-inch supply line is the correct minimum to reliably feed a flushometer-equipped water closet.

When a water closet uses a flushometer, the valve delivers a rapid, high-volume surge of water to flush the bowl. That requires a supply line large enough to carry enough water without dropping pressure at the moment of flush. A 1-inch line provides the needed flow and helps ensure the flushometer can open fully and deliver the intended gallons per flush, even if there’s some pressure loss along the run. Smaller lines, like 1/2 inch or 3/4 inch, would restrict flow and could weaken the flush or cause the valve to operate inconsistently. Conversely, a much larger line isn’t typically necessary for standard installations. So, the 1-inch supply line is the correct minimum to reliably feed a flushometer-equipped water closet.