Why Your Toilet Won’t Flush All The Way

Bathroom plumbing problems are among the most inconvenient issues in your home, especially if you only have one bathroom. When your only toilet is acting up, it can constitute an emergency. 

One common plumbing issue is toilets that won’t flush all the way down. Perhaps the flush is weak, or one flush isn’t enough to take everything down the drain. So, what do you do when your toilet doesn’t flush all the way?

You could always call a plumber, but you can also try out one of these tips for quick flushing fixes. If you fix it yourself, it can save you from an expensive plumbing bill. If you find yourself running into constant problems, it might be better to buy a new toilet that won't clog. Still, with a bit of know-how and a few replacement parts, you can bring full flushes back to your toilet bowl. 

1. Flapper Chain Is Too Short

If your toilet is flushing weakly, the flapper chain inside your toilet tank might be too short. 

The chain connects the flush lever on the outside of the toilet tank—the one you press to initiate a flush—with the flapper on the bottom of the tank. The flapper is a large rubber lid that covers the hole in the bottom. It opens to clean toilet water from the tank into the toilet bowl. 

If the chain connecting your flush lever to the flapper is too short, the flapper might not be rising high enough to completely uncover the hole and empty the tank. This often leads to short flushes. If your toilet doesn’t flush long enough to clear the bowl completely, this is likely the culprit. 

The solution to this is to adjust the toilet chains. Toilets should come with a clip that allows you to change the length of the chain so that your flapper can uncover the tank hole during the flushing process. 

But, if your toilet tank doesn’t have an adjustable chain, you need to replace it. Toilet flapper chains are cheap, and you can buy them at most home stores.

2. Flapper Is Stuck to Its Seat

For the flushing mechanism to proceed properly, the flapper must entirely rise from its seat in the bottom of your toilet tank. This allows the clean tank water to rush into the bowl and flush the waste down into the bowl drain. 

But, if your toilet doesn’t flush properly, your flapper might be stuck to its seal or the bottom of the tank. 

This issue is most common in homes where the water was turned off for a prolonged period, causing the rubber flapper to dry up or stick to the bottom of the empty tank. So, if you recently moved into a new home, lift the lid and take a look inside of the tank. 

Perform a test flush. Is the flapper rising entirely away from its seat, completely exposing the hole in the bottom of the tank? If not, it might be stuck. Reach a hand into the tank —don’t worry, water in the tank is clean— and see if you can unstick the flapper. 

If the flapper deteriorates in your hands, it’s time to replace it. Flappers are easy to replace, and, like flapper chains, you can find them at local hardware stores or online.

Pro tip: Bring your old flapper to the store with you to match the size. 

3. Flapper Closes Too Quickly

Another potential culprit of weak flushes is a flapper that closes too quickly. Take a look inside your toilet tank and perform a test flush. Does the flapper drop right back down onto its seat as soon as you let go of the flush lever? 

If so, it’s closing too fast and not allowing enough water to escape the tank into the bowl.  While you can replace the flapper with a lighter one, the easiest fix to get your toilet to flush properly is to simply hold down the flush lever for a few seconds. If you have a dual flush toilet with two buttons, this might require you to hold one of them longer.

Pressing the flush lever pulls the chain, which controls the rise and fall of the flapper. When you leave the flapper open for a few extra seconds, you ensure that all of the water has left the toilet tank, causing a complete flush. 

4. Not Enough Water In The Tank

If, after exploring all of the potential culprits above, your toilet still won’t flush all the way, you simply might not have enough water in your tank. This is a common issue with compact toilets with small tanks.

The volume of water in the tank determines how strong a flush you get since more water in the tank leads to a stronger push down the drain once the flapper releases the tank water. You should be filling the toilet tank as close to the fill line as possible. 

The fill line is usually printed on the inside of the tank. Take a look inside the tank before you flush, and examine the water level. If it’s well below the fill line, you need more water in your tank. Sometimes, there is also not enough water in the bowl.

Toilets are equipped with a float valve, an adjustable mechanism that controls how much water the fill valve pumps into the tank after you flush. Depending on the kind of float valve you have, like a float ball, there are different steps to adjust it. Be sure to check the owner’s manual for the toilet to learn how to adjust the float valve or float ball. 

Typically though, the float valve will feature a small, white slider that you can raise up or down to control the water volume. Once you move the float valve up, the fill valve should start to add more water, and you’ll hear and see the toilet running. 

Perform a test flush, and adjust the float valve until you get the perfect flush. 

5. Your Toilet Is Clogged

If everything above so far hasn’t fixed the problem, don’t give up yet. The cause of your toilet not flushing all the way might be a hidden clog down in the pipes. 

If waste or toilet paper pieces are left over after you flush the toilet, something can prevent the toilet bowl from emptying. It could be a clog deep in the bowl drain if you flushed down too much toilet paper, something you weren’t supposed to or just mineral buildup over time. 

Give your clogged toilet a few strong plunges to try to loosen up any potential clogs. If you have one on hand, a toilet auger or drain snake can help puncture and break away an aggressive clog.

Sometimes fixing toilet issues is as easy as replacing the tank chain, changing the level of the float valve, or clearing an unseen clog. These issues might also be responsible for similar toilet problems, like when toilet water rises too high.

Even if you try all of the above steps multiple times over and replace every part in your toilet tank yourself, sometimes DIY fixes just don’t work out. If your toilet still isn’t working as expected after trying all of these troubleshooting techniques, it’s time to call a professional plumber for help. 

About the author 

Ryan Thompson is a residential and commercial plumber from Miami, Florida. He has over 20+ years of plumbing experience. He is also a huge DIY enthusiast who does all types of improvement projects around the house.