In-sink garbage disposal units have become quite common in our kitchens, providing a convenient way to get rid of food waste (and providing a constant reminder of how much we like our hands). One might be tempted to think that garbage disposals are a "green" solution to food waste since they return the little bits of food to nature's water stream for little creatures to eat. Right? Um, no.
This article will talk about the environmental considerations of whether to put food scraps in your garbage disposal or your trash can, whether you're hooked up to a municipal sewer system or use a septic system. We'll also give a tip for avoiding that "garbage disposal smell."
The idea that we want to return food scraps—especially the ones that are vegetable matter—back to nature is perfectly correct. But the right way to do that is to compost them out in the back yard.
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If your housing situation isn't conducive to having a compost pile or you just can't muster the will to do it, the choice is then between using the garbage disposal to grind the waste or just throwing it in the trash.
Here are a couple of things to consider:
- The ground-up waste does NOT go back to nature's water supply to be gobbled up by fish and other life forms. It must first pass through the sewage-treatment plant (or your septic system). This not only increases the load on our already overburdened sewage-treatment facilities, the process also removes any food value the waste might have had further down the line.
- It's true that putting the food waste in the trash will shift the burden to the local landfill instead of your sewage treatment system, but landfills are causing us far fewer problems today than sewage treatment systems. The latter are a main source of "nutrient pollution"—one of the main causes of coastal dead zone in estuaries, gulfs, and bays. Adding your nutrient-rich food waste to the sewage stream only makes the problem worse.
- Grinding food uses lots of water, and we're seeing fresh water become a more and more precious commodity.
So, if composting is out for you, put as much of your food waste as possible in the trash can. Avoiding use of the garbage disposal will also help you avoid clogs in it or in the pipes below.
We do make one exception to the rule of minimizing use of the garbage disposal, and that is to address the issue of garbage disposal smell. Over time, a film of scum can form down in the grinding chamber, and it may get a little smelly.
To combat the smell, try grinding the peels from a piece of citrus fruit—orange, grapefruit, lemon, lime—once a week. The mechanical action of the rough peels getting ground up combined with the peels' citric acid—a natural cleaning agent—gets things clean and fresh down there.
The advice to minimize use of garbage disposals applies even more so if you have a septic system. The US EPA points out that garbage disposals add excessive organic loadings to the infiltrative field and other system components (see Table 1). Garbage disposals also lead to a more rapid buildup of scum and sludge layers in the septic tank and increase the risk of clogging in the soil adsorption field due to higher concentrations of suspended solids in the effluent.
Increase in pollutant loading
caused by addition of garbage disposal
You may have a septic system that is designed to accommodate the food waste with additional septic tank volume, tougher service requirements, or other stipulations—for example, a septic tank effluent filter, multiple tanks, or larger infiltration field—but it's probably not worth putting the additional stress on your system. There are few homeowner nightmares worse than having your septic system go belly up!
There's one final exception to our goal of having you use the garbage disposal as little as possible. If you need a clandestine way to dispose of Aunt Wendolyn's pecan-swiss-chard pie without leaving any evidence in the trash can, grind away.
Do you have a relative or friend who is grind-happy in the kitchen? Forward this article to them.
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