What is the problem when the toilet bowl water level reduces significantly with no evidence of a leak>

This usually is an indication of a clog in the line somewhere. Happens at my house when there is a clog in the line.

Mkerwin:

Most often when the water level is decreased to the toilet BOWL it is a result of the REFILL TUBE from inside the toilet TANK falling out/off of the overflow tube.

Check inside tank and see if the refill tube has fallen off. If so, should just be able to re-attach and should be all set.

Otherwise, could be that the holes under the rim of the toilet bowl are clogged... but before we get into how to unclog these... check out the refill tube 1st!

See the picture below to assist in understanding this setup. You also want to check to be sure that the water level in the tank itself is about 1" or so BELOW the rim of the overflow pipe (see picture)

Let me know what you think here.. Mark

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What is the problem when the toilet bowl water level reduces significantly with no evidence of a leak>
A little more information please. Are you saying the bowl fills and then drains down or there is just not enough water in the bowl from jump street? Has it been like this all along or just started? Let me know, Tom