The most common reason that a toilet won't refill completely is that either the fill valve or float isn't adjusted properly as this will cause the valve to close before the tank is full enough. The fill valve is what works to allow water to flow into the tank once the toilet has been flushed.
The main reason for a toilet tank not filling or filling slowly is due to the toilet fill valve. The most common reasons for the fill valve to slow down or no longer fill the tank after the flush are debris issues and the length of time a fill valve has been in use.
If your toilet mechanism has a cylinder float, squeeze the float clip to release the float so you can slide it up or down to the correct level. In addition, if the toilet tank is not flushing all the way, it may be because the bowl's inlet holes are clogged, preventing enough water from entering the bowl from the tank.
First check to see if the float is set too high. Pull up lightly on the float. If the water turns off, that is your problem, just lower the float. If the water does not turn off, you will probably need to replace the fill valve. However sometimes it is just sand or some other pipe debris preventing it from closing.
Improper Float or Fill Valve Position
One of the most common causes of an empty toilet tank is the position of the float or fill valve. The float is designed to rise with the water level, signaling the fill valve to stop water from entering when the tank is full enough.
If your tank uses adjusted cylinders, remove the toilet cap lid and find the fill valve that is located to the left side of the tank. There may also be a clip on the side of the fill valve rather than a screw on top. Pinch the float clip on the side of the float valve and slide it up to let in more water.
Often, the explanation is a clogged pipe, a damaged component, or a hidden leak. No matter what it is causing your toilet bowl to empty, you should address the problem as quickly as possible. Contact a plumber to diagnose why the toilet bowl may empty itself.
Substances like toilet paper and fecal matter will eventually dissolve within the toilet drain and clear the clog organically. However, blockages made from insoluble materials won't resolve on their own and typically require you to fix the clog manually or contact a professional before they worsen.
The Short Answer Is: A slow-filling or incomplete flush in a toilet is often caused by a faulty fill valve or a partially closed water supply valve. When the fill valve is worn out or blocked, it cannot allow sufficient water to enter the tank, leading to slow filling or incomplete refilling of the tank.
If no water comes out the opening with all of the fill valve parts removed, then there is a clog in the line to the fill valve. The next step is to shut off the water and remove the supply line from the bottom of the toilet, then redirect the supply line into your small bowl and turn the valve back on.
A leaky toilet can cause water to escape from the base, leading to a lower water level. This often stems from loose bolts, a damaged wax seal, or a worn wax ring. Addressing leaks promptly prevents further inefficiency or water damage.
Alternatively, you can remove the lid from your toilet tank and fill it with water until it reaches the overflow line. At this point, you'll be able to flush the toilet with the handle like normal. If you're unable to create a flush by pouring water into the bowl, this method may work better.
If your toilet is backing up, it may be due to your tank not having enough water to flush it. Low tank water levels may result from several causes. Damaged water supply lines, broken tank seals, and other issues may prevent tanks from filling completely. Some toilet models may also have low flush strength.
The most common reason that a toilet won't refill completely is that either the fill valve or float isn't adjusted properly as this will cause the valve to close before the tank is full enough. The fill valve is what works to allow water to flow into the tank once the toilet has been flushed.
Solution 2: Vinegar and Baking Soda
Pour about half a cup of baking soda into your clogged toilet and wait for a few minutes. Then, carefully pour in two cups of vinegar. The reaction between the base (baking soda) and the acid (vinegar) should be apparent very quickly.
If the fill valve appears to fill the tank slower than before, then debris has likely blocked the debris screen inside the valve. This will need to be flushed from the debris filter. Turn off the supply to the toilet. Remove the tank lid.
Float Arm. If your toilet's fill valves use float arms, then the fix is to start by removing the toilet cap lid and locate the fill valve in the tank on the left side. Use a flat-head screwdriver to turn the adjustment screw clockwise to raise the fill valve to allow more water to fill in.
DO NOT: Take the flush-and-a-prayer method of flushing again – and again - until the blockage breaks up. Chances are this could lead to overflow. DO: If water is already rising, lift the tank lid and carefully use the rubber floater to block water from filling the hole at the bottom.
After flushing the toilet, you should have about half a tank full of water. While the exact amount of water you'll have will vary, you want to make sure you have enough to cover the bottom of the bowl and enough to sit above the P-trap drain.
Letting a clogged toilet sit too long can result in more severe problems. Beyond the risk of overflow and water damage, the clog could also cause toilet water to back up into other parts of your plumbing system, affecting sinks, showers, and even your home's main sewer line.
Pouring dish soap down a toilet will unclog many obstructions. Pour 1/2- to 1-cup of dish soap directly in the toilet water and wait about 30 minutes before flushing. Follow the dish soap with a gallon of hot water if dish soap alone does not work.
Add hot water
Heat a gallon of water to very hot but not boiling. A drinkable tea temperature is just right. If the water is too hot, it could crack your toilet bowl. Pour the water into the bowl, and let it sit for 20 minutes.
Remove the toilet tank lid and check the trip assembly fastened to the handle. If it's out of place, reposition it. If the assembly is bent, worn or wrecked, replace it. Whether you perform the job yourself or leave it to a plumber, this uncomplicated repair should get your toilet tank filled with water once more.
It's caused by low pressure in the drain or vent line siphoning the water out of the bowl. You'll need a plumber to investigate. Sometimes high winds will produce low pressure in the vent stack, siphoning water from the bowl.