Dilemma: I don't live in San Francisco, where the mandatory composting law is now a year old, and my apartment complex doesn't have a composting bin. So is it worse to throw food scraps into the garbage or down the garbage disposal?

Of course I'll: Throw the food out with the trash; at least I'm not flipping an electric switch to get rid of it.

Trade-off: As food and other organic waste decomposes in landfills, it generates methane, a potent greenhouse gas, and acidic leachate.

Then I'll: Send the scraps down the grinder.

Trade-off: It takes both water and energy to run a garbage disposal; a 2009 article by Consumer Reports suggests that 700 gallons of water are required to run a disposal each year. Additionally, the increased volume of solid waste can put a strain on wastewater treatment plants.

Experts say: It all boils down to how the food waste will be processed. Organic waste that ends up in a landfill may never decompose. "These days, landfills are designed to be dry tombs," says Darby Hoover, senior resource specialist for the Natural Resources Defense Council, adding that methane is rarely captured from landfills. "In most systems, wastewater treatment encourages the processing of sludge to extract energy."

Indeed, a 2008 pilot study by the East Bay Municipal Utility District and the Environmental Protection Agency found that 100 tons of food waste captured daily at a wastewater treatment plant and anaerobically digested produce enough energy to power up to 1,400 homes for a year.

Verdict: Because it has such clear merits over either of these alternatives, don't throw in the towel on home composting just yet. "Even if you're in an apartment, you may be able to put a little friendly pressure on your landlord, or set up your own worm bin, which doesn't take up much space," Hoover says.

But if that's not going to work, the garbage disposal is the best choice, at least in communities where water shortages are not an issue. Always adhere to manufacturer's guidelines for disposal of grease and oils, which can not only clog up the disposal but also cause problems for downstream treatment.