Low water in toilet boil

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    • #276502

      After I flush the toilet, there is the normal 6 or so inches of water in the bowl. If I come back in 2 hours, however, there is only about an inch remaining. What would cause the level of water to drop and how can I fix it? There doesn’t appear to be any leaks and the vent stack does not seem to be blocked. The water level seems to recede regardless of whether other toilets/faucets in the house have been run. This has only been occurring in the last several weeks. Thank you!

    • #294272
      Retired plbg1

      Only 2 things I know and thatis a crack inside the trap are it is being syphoned out. Dont use bowl for awhile and see how low the water goes and when it gets too low and you smell sewer gas flush a toilet and listen and hear if it is got a sucking noise then if it has the water is being syphoned, I dont think it is , it must be a crack.

    • #294273

      RP is correct about the bowl crack or siphonage as likely causes of such a rapid loss of bowl water. Another possibility is negative pressure in the drainpipe. This is rare but can occur with high velocity wind over the stack vent. This causes the water in the bowl to drain out due to difference in atmospheric pressure between the bowl water surface and the waste line. I’ve heard of it, it makes sense, but it is apparently very rare and I’ve never seen such a case.

      I have also seen only a few cracked toilet bowls. They usually manefest with leaks onto the floor that you can see in the bathroom near the bowl. If you can get under the bowl (as in a basement) look for dampened floor boards. The solution is to replace the toilet.

      The most common cause of what you describe is siphonage due to something (especially a rag) that is hung up in the trap. Usually part of the rag hangs over the trap outlet and “wicks” the water into the drain. The best solution is to run a closet auger through the bowl and pull out the rag… I’ve seen that at least a dozen times, so in my opinion it is the most likely culprit.


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