Hey Mr. Green, What's the most ecofriendly way to feed a fireplace? —Joan in Santa Fe, New Mexico

Fueling your fire with sustainably harvested or dead trees may be the best option, but be sure to ignite them in an EPA-approved fireplace insert or wood stove to slash those nasty particulate emissions. And sometimes, as in drier areas like yours, it's better to let dead trees rot; forests may need nutrition from these arboreal corpses.

If you're still using a dirty old traditional fireplace, opt for artificial logs made of materials that might otherwise have been wasted, such as sawdust and wood chips. Because these elements are squeezed together under pressure, the logs are denser and drier than wood, so they burn cleaner and hotter while producing less soot.

Look for manufactured logs made of wood only, and avoid those that contain paraffin, a petroleum-based byproduct with dubious emissions quality. One of the biggest brands, Duraflame, has made its logs greener by phasing out all petroleum-based waxes. Some other options include recycled-paper briquettes (simplefire.com) and logs made of recycled boxes (cleanflamelog.com) and used coffee grounds (java-log.com). If only they smelled like a fresh-brewed espresso.

Hey Mr. Green, My office has four cases of half-liter water bottles delivered each month. Would a water cooler be greener? — Ezra in New York City

Water coolers aren't just good spots for catching up on the latest office gossip. Those jugs generally get reused, while 80 percent of the 25 billion plastic water bottles manufactured every year (using 1.5 million barrels of oil) are thrown away.

Bottled water is an inspiring example of marketing genius; it might also be the craziest form of privatization yet imagined. We're buying plain old H₂O at hundreds, or even thousands, of times the price of tap water because advertising images of clear mountain springs have us convinced that what's inside plastic containers is purer or healthier than what comes out of the faucet.

In fact, it's generally not. According to the Natural Resources Defense Council, more than 25 percent of bottled water sold in the United States is taken from the same public water systems as tap water. And federal standards for bottled water are pretty much the same as for tap; though lead content in bottled water is more strictly monitored, tap water is tested much more often for other contaminants. If you're concerned about the purity of your tap water, check out the EPA's local water-quality reports at epa.gov/safewater. A good certified filter (nsf.org) can take care of most problems at about ten cents per gallon. (If you have well water, however, the Centers for Disease Control and Prevention cautions to get it tested first.)

Filtering your water or refrigerating it overnight in a loosely capped glass or ceramic container will dissipate any chlorine taste or odor, though issues with the flavor may be primarily psychological. In a Good Morning America taste test, New York City tap water beat out bottled water, as it did in other tests I've looked at. So maybe all your office needs is a change of mind-set. For more information, go to sierraclub.org/committees/cac/water/bottled_water.

CONTACT US Read more Mr. Green and submit your own questions at sierraclub.org/mrgreen, or mail them care of Sierra at 85 Second St., 2nd Floor, San Francisco, CA 94105.

Illustration by Melinda Beck; used with permission.