Which of the following is not a commonly accepted method to prevent back-siphonage?

Back-siphonage is a situation where contaminated water is drawn back into the potable water supply due to a drop in pressure. To prevent this occurrence, specific methods are utilized that create barriers to backflow. Among the methods typically accepted are vacuum breakers, which allow air into the system during negative pressure situations, and air gap separation, which physically separates potable water from potentially contaminated sources by a vertical distance. Back pressure units also serve to prevent backflow by ensuring that water pressure in the system remains higher than the pressure from potential contaminants.

Cross-connections, on the other hand, are actual points in a plumbing system where the potable and non-potable water supplies are interconnected. Cross-connections are not methods of prevention; rather, they create a risk for back-siphonage by providing a pathway for contaminants to enter the clean water supply. Therefore, they do not align with the goal of preventing back-siphonage, making them the correct choice for this question.