Toilets, Sinks, Showers, Tubs and Disposals - Toilet Bowl Empty

I have a problem with a toilet. This toilet is in a half bath at the beginning of the sewer line from the house to the street. Almost every week the water in the bowl goes lower and lower and empty. I guess the reason is the vent at the toilet is blocked somehow causing the water sucked into the sewer line whenever water drained between this toilet and the street. Is this the only reason or anything else? I can’t look into it until weekend. Thanks a lot.

Poor venting or no venting of the fixture can cause water to disappear. Vents allow for air flow to the toilet sewage system. Without proper venting, air pockets form in the waste branches and can cause what is called back-siphonage.

Thank you.

Simple explanation. Drains need air to work. If there is no air, they seek the nearest source which is a trap in a fixture (sink, toilet etc). The water in the trap is then sucked out which allows sewer gases to enter the house.
It's kind of like placing a drinking straw in a glass of water and holding your finger over the end of the straw and lifting the straw up. Water will stay in the straw until you release your finger from the end. Same principle for vents. Good luck.

I have this same problem, and I can smell the sewer gasses. How do I vent the toilet??

Thanks,
Kathy

kmmand,
Your toilet should already be vented unless it was added after the house was built and without permits. The vent pipe exits the roof. Look on your roof and see if there is a pipe sticking up through it. Most of the time it will be in the same general area as the toilet is inside. Check the vent to see if it is clogged. The usual cause is birdsnests, spiderwebs covered with leaves etc. This debris should be cleared as much as possible by hands and then flushed with a garden hose. Good luck.