From the Super Mario Wiki
Salvador "Sal" Drainado, (also known as the Duke of Drains and the Prince of Pipes) is a fictional character from The Super Mario Bros. Super Show! The most famous plumber in the Real World, he considers himself to also be the greatest. His skill and contributions to plumbing earned the admiration of many, including Mario and Luigi. Salvador maintains a high opinion of himself and is self-motivated. Rather than play the hero, he places his own needs before those of others in contrast to the Mario Bros.
 Life in Brooklyn
Salvador Drainado's skill and work in plumbing earned him much fame and respect, particularly in his hometown, Brooklyn. As revealed in "Plumbers Academy," he founded the Brooklyn Plumbers Academy, an institution created to teach his craft to other would-be plumbers. After this, Sal suddenly disappeared without explanation.
 Mushroom Kingdom Years
As he would later reveal to Mario, Luigi, Princess Toadstool and Toad in "Brooklyn Bound," Sal found himself stuck in the Mushroom Kingdom with no means of returning himself to the Real World. Over the next thirteen years, he discovered a map to a drain pipe in the subterranean caves of the Snow World that could take him back to Brooklyn. However, upon arrival he discovered that the pipe was blocked by a thick slab of rock. Believing it to be the last drain pipe home, he devised a plan to send a high pressure stream of water at the slab to break through and began building a massive pipe structure throughout the cave that wold serve the purpose.
 Assistance from the Mario Bros.
Mario, Luigi, Princess Toadstool and Toad discovered Salvador Drainado while fleeing from Koopa Khan. Also desiring to return to Brooklyn, the Mario Bros. set to work helping Drainado. Having learned plumbing from Drainado's own Brooklyn Plumbers Academy, Mario and Luigi proved their plumbing ability. The three plumbers made short work of the job at hand and quickly cleared away the wall. Drainado and his new friends continued the search for the drain pipe.
However, Koopa Khan and the Koopa Pack had followed Mario, Luigi, Toad and the princess down into the caverns. As Salvador crossed a rickety bridge over lava, Khan destroyed it with a Bob-omb, sending Drainado and the other four plummeting towards the lava. Mario managed to grab onto an edge and his friends, including Sal, managed to grab onto him. By using a Fire Flower, Mario transformed into Super Mario. Strengthened, he flapped his arms to fly upwards back to the drain pipe's trail and drove back the Koopa Pack with Fireballs.
Continuing down the trail, Salvador finally came upon the drain and boarded it with Mario and Luigi. Mario expressed his doubts about leaving, but Drainado urged him to hurry and emphasized that the drain pipe would only work for a one-way trip to Brooklyn. Eventually, after the Koopa Pack returned and kidnapped the princess and Toad, Mario and Luigi realized they could not leave and exited the drain pipe, bidding Salvador farewell with full knowledge that he would leave without them. Drainado successfully worked the pipe's controls and traveled upward to Flatbush.
 The Super Mario Bros. Super Show!