An insufficient quanity of water entering the bowl
For the siphoning action to get started in a bowl, as much water as possible must enter the bowl as fast as possible. Check to see whether the water level in the tank is as high as it should be. There is usually a mark on the back wall of a tank to indicate where the water level should be maintained. With a lazy flushing toilet you want the water level to be as high as possible without it reaching the top of the overflow pipe. To raise the water level, bend the float ball arm "up" or adjust the clip on the refill valve cup.
An obstruction inside the toilet bowl.
Use a "plumber's friend" (plunger) to try to dislodge anything that may be clogging the passageway of the bowl. Be persistant, it can take quite a few push/pulls to be effective. Apply the force on both the down and up strokes by pushing the plunger forcefully down and then quickly pulling it back.
If this doesn't work, try a toilet auger.
If there is something such as a toothbrush or comb lodged in the bowl passageway, and you can't dislodge it in this manner, the toilet will have to be lifted from the floor. You may be able to reach the culprit from the bottom of the bowl, if not, the bowl will have to be replaced.
Obstruction in the drain under the toilet.
When you have the toilet lifted to examine the underside, always make a visual check in the drain line under the toilet for toothbrushes, etc. that may have made it past the bowl but lodged in the drain. The drain under a toilet is usually 3 to 4 inches in diameter and requires a large "electrically" powered snake....the typical household snake sold by hardware stores and home centers won't do the job.
Tree Roots in the Main Drain
Tree roots in the main drain line are often the culprit. In a recent experience I had with this problem, after exhausting all options, I called on our local "Rocket Rooter" service and watched as he dragged a three foot long bundle of what looked like "heavy duty steel wool" out of the drain. It amazed me that the toilet drained at all after seeing this.
There is an obstruction in the main vent line above the toilet.
When all else fails, you may want to check the main vent line. D.G.M. has this to suggest for making a judgement about the vent ... You can eliminate a clogged drain/vent as the problem with this simple test: Pour a decent size pot of water rather quickly into the bowl. If the sudden addition of the extra water causes a 'normal' flush, then the drain/vent in probably OK.
If you don't get a normal flush after this test, you will need to run a snake through the vent from the roof. The vent is the short pipe you will find on your roof directly above the toilets in your house. This job requires a large snake and climbing up on your roof which can be very dangerous. This job is best left to professionals who have the proper equipment and experience.
There is a buildup of scale in the passageway of the toilet bowl.
A hard crust of scale can develop on the walls of the passageways of the toilet bowl and bowl rim that will restrict and slow the flow of water. The scale is a buildup of mineral deposits from the water. You may have a flower vase or glass that has a coating inside from water that is impossible to remove; this is similar to the scale in a toilet bowl. While you can usually chip away the scale that you can see, there is a layer coating the passageway that you can't reach. This scale restricts the passageways and the holes in the bowl rim and reduces the flow of water. The toilet will have to be replaced ... unless you are willing to take some further rather extreme steps.
Faced with a lazy flush, my son thought there was something stuck inside the bowl passage. He removed the toilet and took it outside to the lawn. He then rolled a golf ball into the bowl and rotated the toilet back and forth until the golf ball came out of the bottom of the bowl. This demonstrated that there wasn't anything obstructing the passageway, and the problem was most likely a buildup of scale. Using a long piece of coat hanger wire, he reamed out all the holes in the rim and then began to scrape the passage with the wire. Although he couldn't see the scale, he was able to loosen a great deal of it with the wire. When he thought he had loosen as much as was possible, he flushed out the rim and bowl with a garden hose. The scale was surprising thick. Not sure he had solved the problem, he re-installed the toilet and was pleased to find the toilet worked as it should.
Disclaimer:
Information provided in these documents is provided "as is" without warranty of any kind,
either expressed or implied, including but not limited to the implied warranties of fitness for a particular purpose.
If there is something such as a toothbrush or comb lodged in the bowl passageway, and you can't dislodge it in this manner, the toilet will have to be lifted from the floor. You may be able to reach the culprit from the bottom of the bowl, if not, the bowl will have to be replaced.
