When you notice the water level in your toilet bowl or cistern sits higher than normal, the high water level may be an indication of a bigger problem with the toilet. Several possible problems, all of which you can solve yourself, can cause high water levels in your toilet as well as other plumbing complications.
If the water level in your toilet's bowl sits higher than normal, the cause may be a partial or complete blockage in the toilet's waste pipe. By pouring a large bucket of water rapidly into the toilet bowl, you can determine if the toilet is blocked or not. If the water drains normally, the toilet isn't backed up. If the water does not drain and you have to stop pouring to avoid overfilling the bowl, the toilet has a blockage that you need to remove.
Even though you poured water in the toilet's bowl and the water drained, if the toilet does not drain quickly and completely, your toilet u-bend has a partial blockage. When the water level rises to a certain point in the bowl, the water will spill over the top of the bend and flow down the toilet's waste pipe. A partial blockage in the bend will keep the water from spilling over into the main pipe as easily, keeping more water in the bowl than normal. Plunging or even using a toilet auger will clear the partial blockage.
When the water level in your toilet's cistern sits too high, it will regularly splash over the overflow tube. The overflow tube keeps the water from spilling out of the top of the toilet's cistern, draining the water into the toilet's bowl as it comes down the overflow tube. The water level in your cistern should sit about 3 cm below the overflow tube, keeping the water from spilling into the overflow tube unnecessarily. You can lower the water level in the toilet by changing the level of the float. If your float sits on the end of a metal rod, bend the end of the rod down. If your float travels up and down on a metal rod, turn the screw on the top of the float so the float travels down.
Flushing power problem
Changing the water level in your toilet will affect the toilet's flushing power. With less water in the toilet's tank, your toilet will flush with less power. Lowering the water level too much in the toilet's tank will lead to more blockages in your toilet. If you intend to save water, keeping the water level so low that your toilet backs up can lead to more flushing which will negate any water savings. Dual flush toilets offer a way to choose how much water you use with each flush, without risking clogging your toilet on a regular basis.