Irrigation systems include but are not limited to agricultural, residential, and commercial applications. SUB Water Division Cross-Connection Control Program Manual and the International Association of Plumbing and Mechanical Operators (IAPMO) classifies lawn sprinkler systems and irrigation systems as a high hazard for several reasons: sprinklers, bubbler outlets, emitters, and other equipment are exposed to substances such as fertilizers, fecal material from pets or other animals, pesticides, or other chemical and biological contaminants. Sprinklers may remain submerged underwater after use or storms. Should the water system pressure suddenly decrease, such as in the case of a water main break, or during a major fire involving multiple fire hydrants, these harmful substances can be back-siphoned into the water distribution system? They may be subject to various on-site conditions such as additional water supplies, chemical injection, booster pumps, and elevation changes. All of these conditions must be considered when determining backflow protection.