Illinois Plumbing Code Practice 2025 – 400 Free Practice Questions to Pass the Exam

The correct temperature for hot water supply systems is 120 degrees Fahrenheit. This temperature is typically recommended to ensure that the water is sufficiently hot for effective cleaning, sanitation, and use in various plumbing fixtures while also minimizing the risk of scalding.

Maintaining the water temperature at this level strikes a balance; it's hot enough to dissolve and remove grease and other residues effectively, which is particularly important in kitchen and bathroom applications, but it's not so hot that it presents a significant risk of burns to the users.

In addition, setting the hot water supply to 120 degrees Fahrenheit helps to optimize energy consumption, as excessively high temperatures can lead to increased energy usage and efficiency loss in water heating systems. Furthermore, the plumbing code often requires this temperature for compliance, ensuring safety and health standards are upheld in residential and commercial properties.