Illinois State Plumbing Practice Exam

Understanding how a bidet receives water helps you see why mixing multiple supply configurations on one fixture isn’t allowed. A bidet should have a single, safe water setup: either hot and cold are provided so you can mix to a comfortable temperature, or a tempered water supply (usually via a tempering valve) is used, possibly with a cold line. The important point is that you don’t feed the fixture with more than one independent water configuration at the same time. The option that combines both hot and cold with tempered and cold would require two separate, active supply configurations to the same fixture, which creates backflow risk and confusion in operation. That’s why it’s not acceptable. The other configurations—hot and cold, tempered and cold, or tempered only—are valid because they represent a single, coherent way to supply the bidet’s water with safe temperature control.