Final answer:
The best unit of measurement for flush fixtures like urinals and water closets is gallons per household per day (gphd) or liters per household per day (lphd) for regular tracking, and kiloliters for annual consumption.
Step-by-step explanation:
The student's question pertains to the unit of measurement used for flush fixtures like urinals and water closets. When considering such units of measurement, especially for tracking water usage, it is essential to consider effective metrics that reflect the volume of water typically used. In the context of household water usage, like toilet flushing which is the highest contributor to indoor water use, the median usage is roughly 125 gallons per household per day (gphd) or 472 liters per household per day (lphd).
However, when considering large quantities of water usage over extended periods, such as yearly family water consumption, kiloliters become a more appropriate unit because of the significant volume involved, similar to the volume of a swimming pool. Conversely, when contemplating the capacity of standard bathroom fixtures like bathtubs, liters are a more suitable unit than milliliters due to the size of the fixture and the amount of water it can contain.
In the United States, the customary system is frequently used, which includes units like gallons. Therefore, for practical applications within the US, gallons might be a typical unit for flush fixtures. However, the metric system, using liters and kiloliters, provides a standardized unit of measurement that can be universally applied, as in the case with the historical art piece Fountain by Marcel Duchamp, a porcelain urinal which has become an iconic piece of modern art.