Alligators live in sewers and can come up into your toilet.

False. This urban legend originated in New York City (something about a batch of imported baby alligators flushed down a toilet…), but according to Ian Michaels, spokesman for the city’s Department of Environmental Protection, which oversees water and sewer systems, “there are no alligators in the sewers.” Alligators are cold- blooded, he adds, and the temperature in the sewers in winter would be too cold for them to tolerate.

Even where one might more reasonably worry about gators — say, in Florida — a call to Frank Calderon, information officer for Miami-Dade County’s Water and Sewer Department, yielded a dry “No, no alligators in the sewers” before the question was even asked (“You have no idea how many times people ask us that”). He says that the methane and hydrogen sulfide gases that accumulate in sewers make for an “inhospitable environment.” They displace oxygen, so there’s none for alligators to breathe; nor is there anything for them to eat. And even if an alligator donned a gas mask and brought its own rations, it would have to be a contortionist to work its way into your bathroom via the toilet. Most sewer-line pipes coming into homes are only four or six inches wide, and the internal trap in toilets makes the opening a mere two to three inches. So you can confidently flush this myth once and for all.

The bumps and creaks you hear are the house settling.

Could very well be true. A new house is constantly adjusting to the land beneath it with subtle shifts and moves. More likely, you’re hearing the boards in floors and walls expanding as they heat up and contracting as they cool, or expanding in humid weather and shrinking in dry, creaking as they shift against the nails or one another, says Mike Litchfield, author of Renovation, 3rd Edition (Taunton Press, $40, www.amazon.com). Still, it’s wise to pay attention to these sounds, advises Judy Ostrow, author of The House That Jill Built: A Woman’s Guide to Home Building (Gibbs Smith, $25, www.amazon.com): Creaking could signal a loose floorboard, and crunching or scratching sounds could indicate the presence of rodents or insects.

You should clean the lint trap before using the clothes dryer.

True. “The lint filter covers an exhaust port,” says Litchfield. “If it’s blocked with a layer of fuzz — and all it takes is a load of towels to make one — the moist air can’t get out. It’s a tremendous waste of energy, because it takes longer for clothes to dry, and there’s a remote possibility of fire.” Also, residue from dryer sheets and detergent can decrease performance by forming an invisible layer on the trap, says Jill Notini of the Association of Home Appliance Manufacturers. She suggests taking a nylon brush and hot, soapy water to the screen regularly.