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  1. KOHLER
  2. Toilets and Seats
  3. Troubleshooting

Poor Toilet Flushing Due to Insufficient Venting

Overview

NOTE: Older toilets used the force from a greater volume of water to remove waste, while newer toilets require adequate venting to remove waste.

The following symptoms are signs of a clogged waste stack or vent pipe:

  • Water rising in the toilet bowl
  • Slow flush (bowl water rises quickly, but falls slowly)
  • Frequent clogs
  • Having to hold the handle down to get a proper flush
  • Sounds coming from other drains in the area when the toilet is flushed
  • Bubbles coming from the trapway opening during the flush

Bucket Method

One way to check the waste stack is to take a large bucket of water and dump it in the toilet bowl. If the toilet flushes well, there may be a restriction within the vent pipe that will need to be cleared. If the water still drains very slowly, there may be a clog in the waste stack.


P-Trap Method

An alternate way to test for a clog or venting issue is to check the P-trap.

NOTE: This test will not work if the sink's P-trap is not located on the same vertical waste stack as the toilet.

  • Locate the P-trap below the bathroom sink.
  • Place a bucket below the P-trap to catch any water that may spill.
  • Unthread the P-trap at point 1 (Fig. 1).
  • Swivel the P-trap pipe at point 2 (Fig. 1) to expose the opening from point 1.
  • Flush the toilet five to six times.
  • If the toilet flushes better with the P-trap open, the vertical vent pipe is blocked.
  • If any debris comes out of the pipe from the wall, there may be a partial or full clog in your waste stack, or you do not have sufficient venting.
  • If the P-trap method is not successful, contact a licensed plumbing professional.

1388573-10-B  ©Kohler Co.

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