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hohadcr 12-20-2009 01:03 AM

Toilet backfill after flushing
Hi, everyone, we have a toilet that flushes fine. The problem is after flushing down, while the water tank is filling up with clean water, some clean water backs up in the toilet bowl till the point it chould almost flood. Then the water in the toilet bowl goes down and the water tank keeps filling up then all goes back to normal: little water in the toilet bowl and the tank fills up.

Does anyone have any idea of what could be wrong? Maybe something in the water tank? Then how to fix it?

This is a 2nd floor toilet in a 3 storey old building, where i believe the 2nd and 3rd floor toilets are in the same position and use wet venting on stack of each other.

If there is venting problem above the 3rd floor toilet, the 3rd floor would have the same problem. But 3rd floor toilet is fine. If there is somethign blogged between the 2nd and 3rd floor, the 3rd floor toilet would have flushing problem. but there is none.

So if it is still venting problem, where the blockage in the venting could be?

Thanks alot

AllanJ 12-20-2009 07:04 AM

There are actually two problems here.

If the toilet flushes OK but a moment later the bowl fills to where it threatens to overflow onto the floor, you probably have some problem with the venting in the plumbing beyond the toilet. There is generally a vent pip extending up to and through the roof and dropping a fish line and sinker down can detect the presence of a blockage. Also try using a toilet plunger just in case there isn't a movable mass partially blocking the toilet drain pipe proper. You will need to use fast and forceful pushes and yanks with the bowl almost full (the rim of the plunger submerged) but of course need to be careful you don't crack the toilet bowl.

As the toilet ank refills some wahter should be put down into the bowl via a thin tube coming from the fill mechanism. Excessive water put down should not be a problem other than running up your water bill. You may also watn to check whether the flapper is closing promptly after the flush, again the only disadvantage is running up our water bill.

Thurman 12-20-2009 07:42 AM

FWIW; two votes on the vent piping problem. Check it out. David

majakdragon 12-20-2009 10:28 AM

And a third vote for a vent problem OR a partial clog a few feet from the toilet in the drain line. Normally, a vent problem will be accompanied by air bubbles appearing in the bowl.

hohadcr 12-20-2009 11:25 AM

if it is still venting problem, where the blockage in the venting could be?

majakdragon 12-20-2009 02:23 PM

If it is safe to do so, go onto the roof with a flashlight and check the vent pipe. It may be a birds nest, leaves or even spiderwebs covered with condensation that froze. Remove anything you can by hand, and if necessary, flush out the line with a garden hose.

hohadcr 12-20-2009 04:01 PM

New development.

I looked lower into the toilet bowl and saw some toilet paper. I plunged a couple of times, toilet paper was gone, and ... it does not back fill again!!

I also got to know that once someone took a big dump in the toilet and it didn[t want to flush down easily.

Now is it not about the venting, and about the drain? Maybe the old drains are clogged a bit or sth?

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