Final answer:
The question refers to the plumbing systems' concept of Fixture Units (FU), which measure the hydraulic load of fixtures. Fixtures with 1.5 FUs or less can be grouped together or connected to smaller drain lines due to their minimal waste water discharge.
Step-by-step explanation:
The question pertains to plumbing systems, specifically the determination of acceptable hydraulic loads for certain fixtures. In plumbing, the term 'Fixture Unit' (FU) is used to represent the load that a fixture places on the sanitary drainage system. One fixture unit represents the equivalent load of one cubic foot of water drained in an area of one minute. When dealing with fixtures that have a hydraulic load not more than 1.5 FUs, these are typically fixtures with a very low flow rate or discharge, such as a small sink, and can be grouped together or connected to smaller drain lines because they discharge minimal waste water.