Step 1: Remove the lid of the toilet tank.
Lift the toilet tank lid and place it on a safe, flat surface — inside the bathtub or shower or on top of the bathmat is ideal. Toilet tank lids are ceramic and are easier to break than you think, so be careful.
You should be able to see the flushing system inside the tank with the lid off.
Step 2: Check the water level inside the tank.
Most toilets are designed to work well with a water level between 0.5 to 2 inches below the overflow tube and fill valve. Some tanks will have an etched line indicating where the water level should be.
You can use a pencil to make a mark to show where the level is, or you can write down a measurement from the top of the overflow tube to the water level.
Step 3: Turn off the water supply.
Every toilet has a shut-off valve, usually located behind or beneath the toilet on the water line. When you find the oval knob, crank it clockwise until it doesn't go any further.
Once it's closed, flush the toilet or lift the valve chain in the tank. With the tank empty, you can now examine all the parts easily.
Step 4: Determine what type of valve and float system your toilet uses.
Flushing and float systems come in several different forms. The two most common are the ball-and-arm float and the cylinder float (also known as a float cup).
A third, newer system is the floatless system that uses anti-siphon, pressure-sensing valves. This last mechanism is more expensive, less reliable and usually requires a professional to adjust:
- Ball-and-arm floats (sometimes called a ballcock valve): A ball-and-arm float looks like a ball or balloon on the end of a metal arm. The arm is usually metal and extends from the refill pipe, and on the end will be the ball float.
- Cup or cylinder floats: A cylinder float is a mechanism that wraps around the refill pipe, moving up and down with the water level in the tank.
- Floatless (internal) fill valves. The easiest way to tell if this is your type is that there is no visible float mechanism — the float is inside the vertical cylinder.
Step 5: Inspect all of the parts inside the tank.
Examine each part of the flushing mechanism, especially the toilet fill valve and the float. It may be time to replace the part if you see any obvious signs of damage or wear.
Examine the ball float carefully, looking for any cracks. A light shake will tell you if there is any water inside. If there is, the ball will need to be replaced.
Step 6: Adjust the water level in the tank.
Each type of valve assembly is adjusted in a slightly different way. If this is your first time doing DIY toilet repair, go slow and be gentle to avoid doing more harm than good.
Ball-and-arm float adjustment.
Your float valve (located on the top of the fill valve) should have an adjustment screw visible from above.
Depending on where the toilet water level is in your tank, you will want to turn the screw clockwise or counterclockwise. Turning clockwise will raise the water level, and turning counterclockwise will lower it. Only turn the screw one rotation at a time, then flush the toilet to see if it works efficiently.
Some ball floats on a metal arm can be adjusted by gently bending the arm. But getting the level right this way can be a real challenge.
Float cup or cylinder float adjustment.
The cylinder float might have a release clip extending from the side of the cylinder. To adjust the float's position, press or squeeze the release and move the cylinder to where you want it.
If there's no release clip, look for an adjustment dial on the side of the cylinder with a stem leading to the float valve above. Rotate the dial clockwise to lower the height or counterclockwise to raise it. Flush the toilet with every rotation until you have achieved the right level.
Floatless (internal) fill valve adjustment.
Unlock the fill valve by gently turning the upper half of it counterclockwise. Once it's in an unlocked position, you can raise the top of the valve to raise the water level.
Flush the toilet to make sure you have the level dialed in right, and when you do, simply turn the valve clockwise to re-lock it.
Hire a plumber near you.
If you're having toilet issues that feel beyond your ability to DIY, download Thumbtack and hire a nearby plumber to take care of it for you. Life is too short to be stressed out by a temperamental toilet.
FAQs
What causes low water levels in a toilet bowl?
Low water levels in toilets are most commonly caused by a damaged fill tube, which shuts off the water flow before the tank fills. Other causes could be improperly adjusted float arms or float height. A flapper that's not properly seated can also create low water levels. All of these common issues can be simple to fix.
More complex issues include clogged inlet holes or blocked sewer vent pipes. Sometimes, low water levels indicate a crack in the toilet bowl and/or pipes — serious problems that mean it's time to hire a professional.
How high should the water be in a toilet bowl?
Most toilets operate best at a level from 0.5 to 2 inches below the fill valve or overflow tube, but the optimal water level in a toilet depends on the toilet itself. Some toilet bowls operate with a higher water level than others. However, if your toilet bowl water level changes, you can be sure something is wrong.
Can I add water to the toilet tank?
Why doesn't my toilet bowl fill after flushing?
A toilet bowl that doesn't fill after flushing is usually the result of a broken or worn-out flapper or a valve. Valve issues usually involve either faulty fill or closed supply valves.
Low water pressure can also cause the toilet to fail to fill after flushing. Additionally, overflow tube issues and problems with the float ball or cylinder can contribute to toilet bowls that refuse to refill.
Most of the time, low water levels in toilet bowls are quickly and easily repaired. However, if you don't feel confident doing DIY repairs or have the time or desire to tackle it yourself, you'll want to hire a pro.
