Commercial water closets shall not exceed how many gallons per flush?

• A. 2.5 gpf
• B. 3.0 gpf
• C. 3.25 gpf
• D. 3.5 gpf

Answer: (D)

Maximum flush volume for commercial water closets is what this item asks you to recall. Commercial toilets are built to handle heavy use, so codes allow more water per flush than residential models. Residential toilets are limited to 1.6 gpf, while commercial units carry a higher ceiling to ensure reliable flushing in busy settings. The standard upper limit for a commercial water closet is 3.5 gpf, so that is the maximum amount permitted. While newer, more efficient models with lower flush volumes exist, they must still meet performance standards, but the question is about the maximum allowed, which is 3.5 gpf.