Forty-eight years ago, I learned a valuable lesson as a plumbing apprentice. I had just begun my career in the mechanical trades when I was dispatched to lend a hand cleaning a kitchen sink drain in an apartment building. 

The building had 12 apartments on three floors with kitchens aligned vertically so that each 2-inch cast iron stack served three kitchens. The gentleman on the third floor had been fishing and brought home a bunch of fish that he proceeded to gut and descale in his kitchen sink while washing the scales and guts down the drain. No garbage disposal, so the swirling mix of guts and scales went down until they didn’t. That’s when we were called in.