Our house is 5 yrs old. When our washer drains, the water in the toilets bubbles up onto the toilet seat lid. When the washer is not running, the water in one toilet will swish back and forth and drain until there is almost no water left. Plumbers can't find a problem.
Robin N. - Ridge Manor, FL
Robin, I'm not a plumbing contractor, but it sounds to me like you might have a problem with your waste vents. The drainage system in a home is actually fairly simple: most waste lines drain due to gravity with a little help from air that enters the piping. The air comes in through vents that normally extend up through the roof.
When a fixture such as a toilet or tub backs up or empties very slowly, it's usually an indication that there is a blockage in the waste line for that particular item. If the entire house is backed up or all of the fixtures drain slowly, the problem may be with the main sewer line to the street or septic system. However, when the issue is as you describe where draining one fixture affects the water level of other plumbing devices, there is a good chance that the venting isn't operating properly.
If the problem has existed since you moved into the home 5 years ago, it's possible the venting has never been correct. Correcting the issue can be simple or a little more involved. A squirrel or bird nest blocking a roof vent can usually be easily removed, but if you have a high roof, the task should probably be done by a professional contractor. It's also possible that some debris such as leaves or twigs could be causing the clog.
However, if the original venting was done improperly, you're going to need an experienced plumbing contractor. They'll need to look at the locations of your fixtures and rely on their knowledge to determine where vents should be located and how large each should be. If a vent needs to be added, there's a good chance there could be some sheetrock repairs. You may also need a roofer to install flashing around the new piping to prevent possible water intrusion.
The good news is that once plumbing vent problems are corrected, they rarely ever need any additional attention.