A: Plumbing disasters during a party or large family gathering are more common than you might think, as the extra people in your home create more water in the kitchen and bathroom. This extra water and waste often overwhelms partially clogged drain lines.
I’ve been a master plumber since I was 29 and have a love-hate relationship with garbage disposal. They’re handy machines when you don’t want to throw away leftover food, but they can damage your drainage systems if used improperly.
Using an incomplete analogy, let me explain what happens when you use your garbage disposal. Imagine a huge ready-mixed concrete truck filled with sand, small stones, and water. Drop the chute and discharge this mixture into a city canal that is 12 inches in diameter. If you do not add a significant volume of plain water immediately after draining sand and gravel into the sewer pipe, the pipe will begin to suffocate. The clear water is needed to transport sand and gravel to the end of the pipe.
Use a clear blender to create a more realistic example of what is happening in your disposal. Save about a pint or even a quart of leftover food that you would normally shovel into the dark black hole of disposal. Put enough water in the blender to make a leftover smoothie. This food sludge is exactly what your disposal creates – and you hope it magically flows down your kitchen drain pipe!
Eggshells and celery are two of the worst things to throw away in the kitchen. The eggshells are similar to the small stones and sand I described above. Celery has tough strands of fiber that can wrap around the moving parts of the disposal. I would never throw away any of those leftovers.
It is very important to understand that the interior of many kitchen drain pipes is by no means smooth and wide open. The insides of old galvanized iron drain pipes develop flake over the years. A steel pipe that was originally 1½ inch inside diameter could, after years of use, have an inside diameter of only half an inch or three quarters of an inch. I saw these horizontal and vertical pipes completely clogged with debris.
Modern plastic PVC or ABS plastic pipes can also have deposits, especially hardened grease, that clog them. Expecting a slurry of ground food like water to flow through partially clogged drains is the same as expecting three people to get smoothly through a conventional doorway at the same time.
In my opinion, the best way to use a garbage disposal is to add the leftover food you want to grind up and then put the stopper on top of the opening so you can fill the sink halfway with water. When you’ve added the water, pull out the stopper and turn on disposal immediately.
The spinning, cutting heads in the disposal turn the food into a slurry, and the weight and volume of the clear water in the sink begin to push it down the drain line. The added benefit is that the clear water flushes the disposal sides when the last food leaves the machine on its way to the sewage treatment plant. I would then let the tap water run for at least 30 seconds after all of the water in the sink has drained.
I’m not a big fan of septic tank disposal. There are two schools of thought, and years ago a major waste disposal company created a disposal system that releases special enzymes to engulf the slurry as soon as it enters the septic tank. Installing a new leach field is very expensive if you overfill your septic tank with organic matter. In my opinion, it’s a lot easier to compost or throw away leftover food.
The secret to a fresh smelling garbage disposal is to keep all internal parts clean. You do this by making sure the disposal is rinsed with plain or even soapy water after the food has been ground as described above. It’s not difficult to imagine the vortex of spinning water, much like you see it in a mixer flushing the disposal sidewalls as the water exits the sink on its way to the drain pipe.
Here’s another tip to help prevent party disasters. Every two months or so, I pour 10 gallons of boiling water into my sink to keep the inside of the drain pipe as clean and grease-free as possible. I store partially soiled paper towels and use them to soak up grease from all pots, pans, and plates so that I put as little grease as possible in my drain lines. While we plumbers are almost all great people, we want to be with our families for Christmas, rather than on our knees disassembling your sink’s drain pipes!
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