Clogged drains in a home or business are a normal occurrence. Most drains work just fine for many years. But over time debris builds up in the drain and forms a black sludge that sticks to the side of the pipes. Over time this black sludge builds up and greatly diminishes the inside diameter of the pipe. A 2" sink drain over time will actually only have an inch of room for the kitchen waste to flow through.When people use their garbage disposals to chop up food wastes and flush them down the drain the drain internal capacity eventually will not be able to handle the solid vegetable debris and will cause a clogged drain.