Toilet Repair Signs of Poorly Vented Plumbing Drain Lines. Solutions to a bubbling toilet or changes in the water level in the bowl . Next Project ‘ Solution to a bubbling toilet and sudden water level changes in the toilet bowl. Both indicate an air venting problem in the drain system. By the DIY experts of The Family Handyman Magazine. Signs of and solutions to a toilet venting problem.Q The water in my toilet bowl keeps draining out on its own. How do I take care of this toilet repair?.This means the toilet vent pipe is clogged or partially clogged. A tennis ball, dead bird or twigs thrown by a mischievous son might have dropped down into the rooftop vent pipe may be the problem. Drop a small flashlight that is SECURELY attached to a strong string or wire down the pipe. Look for a clog. Run garden hose water down the rooftop . When the vents in a plumbing drain system are clogged, partial blockages can cause pipes to gurgle. That gurgling sound should alert you to vent problems..