Final answer:
The size and material of irrigation water piping installed outside of any building and separated from the potable water supply are determined by various factors such as water pressure, environmental conditions, and local building codes.
Step-by-step explanation:
The size and material of irrigation water piping installed outside of any building and separated from the potable water supply by means of an approved back flow prevention device is determined by various factors such as water pressure, environmental conditions, and local building codes. Typically, PVC (polyvinyl chloride) pipes are commonly used for irrigation systems due to their durability, affordability, and resistance to corrosion. The size of the piping depends on the required flow rate and the distance over which the water needs to be transported.