Which of the following is an example of a non-potable water application?

Irrigation is indeed a prime example of a non-potable water application. Non-potable water is water that is not suitable for drinking but can be used for other purposes, such as agricultural uses or landscaping. In this case, irrigation involves using water to nourish plants, which typically does not require the water to be treated to the same standards as drinking water.

This distinction is crucial in plumbing and water management practices because it allows for the utilization of sources that are safe for plants but may contain impurities or chemicals not suitable for human consumption. Understanding the difference between potable and non-potable water helps in managing water resources effectively and ensuring public health and environmental safety.

Other options mentioned, such as drinking water supply, cooking water, and water for bathtubs are all examples of potable water applications, where the water must meet specific health and safety standards for human use.