Gene Goforth sells showerheads—big ones, like the Raindance Imperial 600 AIR. Selling for as much as $5,457, it has a 24-inch spray face, 358 no-clog channels and a triple-massage option. "You can just stand under it, and it helps your psyche," says Mr. Goforth, who has one in his home. Now, Mr. Goforth is in a lather over the federal government's tough new line on water-hogging showerheads, part of a new effort to enforce energy- and water-use regulations. "Leave my shower alone," Mr. Goforth recently wrote in a letter to the Department of Energy. Regulators are going after some of...