What is the required flow rate, in gallons per minute, at a point of outlet discharge for a water supply outlet provided for a water closet, flushometer tank?

The required flow rate for a water supply outlet serving a water closet that is equipped with a flushometer tank is designated as 1.6 gallons per minute (gpm). This standard is based on the design and operational characteristics of flushometer tanks, which are specifically engineered to deliver a sufficient volume of water quickly to ensure effective and efficient flushing.

Flushometer tanks utilize a mechanism where water is released at high pressure to create a powerful flush, and the 1.6 gpm flow rate is considered optimal for removing waste while minimizing water consumption. This rate is part of efforts to promote water efficiency without compromising performance.

In residential plumbing, adhering to the flow rate outlined in the International Residential Code ensures that fixtures operate as intended while aligning with conservation efforts. Choosing a flow rate higher than 1.6 gpm might lead to unnecessarily excessive water use, whereas a lower rate could affect the toilet's flushing effectiveness, causing operational issues. Therefore, the 1.6 gpm specification is the correct answer in this context.