What does the term "Plumbed backwards" mean?
Simply put, waterlines that attach to the "inlet" and "outlet" on the filter canister were reversed during installation. In this case, the water flow through the filter element will be from the "Inside-out" rather than the "outside-in" (as the filter was intended). Debris rapidly accumulates on the inside of the pleats, water flow is restricted, and the cartridge begins to expand. Eventually, the cartridge's end cap will split, releasing the internal pressure. The filter element is now being by-passed in the filtration cycle.