Water closets, also known as toilets, are fixtures that use water to flush human waste into a sewer or septic system. The unit of measure for water closets is gallons (liters) per flush, which indicates the amount of water used for each flushing cycle. The water efficiency of water closets can vary depending on the design, technology, and regulation of the fixture. The LEED rating system encourages the use of water-efficient fixtures that reduce water consumption and wastewater generation12. Reference: LEED v4 Green Associate Candidate Handbook1, EPA's WaterSense Toilets2