Toilet clogs are a common plumbing problem. The fact that you may not be able to tell if the toilet is clogged can be very frustrating. Here are some ways to check if your toilet is clogged. The most obvious way to check if your toilet is clogged is by inspecting the water level in the bowl. If it's low, then it's safe to say that there's a blockage somewhere in the system and you should call a plumber or try some of these DIY fixes! Another way to tell if your toilet is blocked is by looking at the water coming out of the overflow hole on top of the tank. If water isn't flowing through this hole, then there's probably a blockage and you should call a plumber or try some DIY fixes.