Problems With Water Levels & Flushing in Toilets

Low water in the bowl may mean a partial blockage in the toilet.


Optimum water levels in both a toilet's tank and bowl are the keys to proper flushing. You'll get a good flush if there's too much water in the tank but not if there's too little. Both high and low levels in the bowl point to blockages and problems with flushing.

Tank Levels

The optimum water level in the tank is usually about an inch below the top of the overflow tube. If the water is lower than that, there may net be enough to fill the waste pipe and create the suction that empties the bowl. You can raise level by screwing the float ball clockwise to make the float arm shorter. If you have a cup float, shorten the rod connecting it to the fill valve. Either adjustment will make the fill valve stay on longer when the tank is filling.

Bowl Levels

The bowl level is governed by the height of the P-trap outlet inside the toilet. When the level is higher than it should be, it usually means there's a blockage in the waste line. When the level is too low, that can also point to a blockage, but it's usually in the P-trap, where it's siphoning water from the bowl. Either way, the toilet won't flush properly until you remove the blockage, either by plunging, using an auger, reaching in and grabbing it or pulling the toilet.

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