Dear EarthTalk: I was surprised to learn recently that some cities, including New York, have outlawed kitchen-sink garbage disposals, at least in homes. I would have thought these machines were Earth-friendly. What's the deal?
--Maggie Mangan, St. Louis, MO
Kitchen sink garbage disposals are not necessarily Earth-friendly in and of themselves, but they do play a valuable role in grinding up food scraps into small enough bits for local sewer or on-site septic systems to handle. In the U.S. overall, about half of all homes have a garbage disposal in the kitchen. New York did outlaw the devices for many years, thinking a ban would alleviate the strain on the city's aging sewer system. But a study later conducted in the mid-1990s found benefits to lifting the ban, including a likely reduction in rat and cockroach problems and a reduced flow of solid waste to landfills already bursting at the seams. So in 1997 the Big Apple began allowing the devices again.
But garbage disposals are not the greenest way to dispose of food waste. According to Mark Jeantheau of the popular eco-website Grinning Planet, conscientious consumers interested in returning food-based nutrients back to the Earth should bypass the garbage disposal in favor of composting.
"The ground-up waste [in a garbage disposal] does not go back to nature's water supply to be gobbled up by fish and other life forms," he says. Sewage-treatment and septic systems remove "any food value the waste might have had." Indeed, most modern-day sewer filtration systems utilize chemicals to rid the outflow of any life forms, beneficial or otherwise. Plus, grinding food in a garbage disposal uses a lot of freshwater, which is becoming a more and more precious commodity.
Those on their own septic systems also might want to minimize their use of the garbage disposal. According to the U.S. Environmental Protection Agency (EPA), regular use of garbage disposals leads to a "more rapid buildup of scum and sludge layers in the septic tank and increased risk of clogging in the soil adsorption field due to higher concentrations of suspended solids in the effluent." Jeantheau adds that even if a given septic system is designed to handle heavier, food-based loads, it still might not be worth the risk: "There are few homeowner nightmares worse than having your septic system go belly up."
While composting may sound like a messy proposition, it doesn't have to be. For starters, those doing the dishes should make sure to dump any and all food waste items into a kitchen-based composting bin with a lid that seals tight. Many municipalities now make such bins available to interested residents. A mesh strainer in the hole in the sink can catch smaller food scraps and be dumped into the composting bin when the dishes are done.
When the kitchen-based compost bin fills up, it can be dumped into a larger composting bin outside. After four to six months, you should have some nice compost to add to your garden and jumpstart the health of your soil. Companies such as The Compost Bin and Clean Air Gardening offer online sales of a wide variety of quality compost bins of different shapes and sizes, and provide a wealth of comparative information for the interested consumer.