How to Troubleshoot Toilet Problems

The toilet is an often overlooked mechanical marvel of the home. While it's used regularly, it isn't always maintained regularly. When you hear the water trickling in your toilet, or you just can't seem to figure out what's causing the leak that runs down the base of your throne, follow these steps to diagnose the problem.

Diagnose a Leaky Toilet

Start at the source of the water. Check the supply line that runs into your toilet by feeling it for moisture. If it's wet, it is possibly the source of the leak. Old supply lines crack where they're crimped and bent.

Check the area of the toilet's tank where the supply line enters to make sure it isn't wet before replacing the line. Your leak could be coming from a loose or cracked bolt under the tank.

Feel around the bottom of the tank for any cracks or wet areas.

Concentrate on the area under or around the base of the toilet bowl if that's where you're seeing water. Lift up and reseal the bowl when water is leaking through the bottom.

Diagnose a Noisy Toilet

Watch the water as it gets flushed down the toilet. If it seems to stop suddenly or flushes very slowly, your toilet may have a clog or obstruction in the water tank.

Check the ball float mechanism inside the toilet's tank. Take the lid off the tank, and watch the ball as you flush the toilet. Make sure there are no cracks or weak areas in the mechanism, and replace it when defective.

Oil the flush lever or ball float mechanism if it seems to be sticking or not working properly.

Diagnose a Clogged or Poor Flushing Toilet

Remove anything you know has been accidentally flushed down the toilet or may be plugging the toilet by plunging it out. Use a plumbing snake when unsuccessful with a clog or call a plumber.

Make sure your ball and float is working properly by removing the tanks lid and lifting the ball up. This should cause the plug to open at the bottom of the tank and water to fill the tank.

Check for any leaks between the tank and the toilet bowl. Notice any running water down the base of the toilet or out the back side.

Diagnose a Running Toilet Problem

Check the float inside the tank by removing the tank cover. Make sure the float arm is going up as far as it should to properly close the bottom seal.

Feel the float ball to make sure it doesn't have water inside. This would make it sink and not shut off the bottom valve properly.

Look for corrosion or cracks in the shut off valve.

Make sure the ball and float mechanism isn't damaged, bent or missing parts. If it is, replace them.


  • It's best to shut water off before tightening or replacing any parts on your toilet to avoid a water leak while working.

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