Q Until recently, our commode was working fine. But lately we cannot get it to flush, even with little paper in it. The water just goes around, but it won't go down. We have tried using a bucket of water and a plunger and finally are able to force down everything. There is just no downward suction. We have a 5,000-gallon septic tank, and it was cleaned about six months ago. What could be the problem? -- Tonya

A Here are three possible causes:

* Although the septic tank is large and was recently serviced, it is possible that the leach lines are clogged, preventing the liquid effluent in the tank from draining into the subterranean leach field. If that's the problem, however, you would probably have noticed drainage problems with other fixtures, such as bathtubs, showers and sinks, not just the commode. But just to be sure, contact the people who pumped the tank six months ago to confirm that they tested the leach system.

* The drainpipe from the toilet to the main septic line may be clogged with roots or other foreign matter. That line should be checked by a plumber to ensure that it is unrestricted and fully operational.

* A small unauthorized object may be stuck in the toilet trap. As any curious, thrill-seeking first-grader can tell you, no one can resist the fun and suspense of watching a toy descend into the swirling, aquatic abyss. If some such object is lodged in your toilet trap, it may be necessary to detach the bowl from the floor. Hire a plumber to do this.

When we built our home, we opted to have our washer and gas dryer in the upstairs hall closet. Our builder ran the dryer exhaust pipe directly through the roof, rather than through an outside wall.

This has turned out to be a problem, because the attic is vented at the roof ridge, and the vent screen becomes clogged with dryer lint. Every few months, I have to go into the attic to clean the screen.

I've been told that the installation meets code, but I'm not convinced. Does this sound to you like a proper way to install a dryer vent? -- Ira

Your description of the clothes dryer vent in your home is puzzling in one respect. You say the builder "ran the dryer exhaust pipe directly through the roof." Yet you are able to remove the lint from inside the attic. If the pipe extends through the roof, rather than ending in the attic, then the lint should be on the outside of the screen. That should be accessible only from outside the building, that is, from the roof.

Having said that, your best bet is to have the entire dryer exhaust installation reviewed by a qualified third party. An experienced home inspector should be able to determine the efficacy and appropriateness of this vent. Even if it complies with code requirements, it may be installed in a manner that is impractical or functionally problematic. Although legal, it may warrant improvement.

Barry Stone is a professional home inspector. If you have questions or comments, contact him through his Web site, www.housedetective.com, or send mail to 1776 Jami Lee Ct., Suite 218, San Luis Obispo, Calif. 93401.

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