A common pitfall here is forgetting to account for the 3/4 to 1 inch of pipe that goes inside the fitting, Hiller says. “The best way to size it is to make sure the pipe and fitting go together ...

I used PVC for decades, and it’s fantastic material. As you might expect, it comes in different sizes. The most common sizes you’d use around your home would be 1½-, 2wo-, three- and four-inch.