Is Your Toilet Bowl Slowly Losing Water? (Fix It Now!)

Plumbers are a godsend whenever the kitchen sink or the toilet isn't working, but are difficult to get in contact with on occasion. If your toilet slowly leaks water, you will need to take immediate action. Whether it be a cracked bowl or a clogged vent, let’s take a look at what you can do when your toilet slowly loses water.

Toilet Bowl Slowly Loses Water

If you walk into your bathroom and see that your toilet bowl has lost water, don’t immediately call the plumber. There are some things you can adjust to solve the situation. However, if you find that your issue is more serious, contact a professional to prevent lost money and time.

If your toilet bowl is slowly losing water, it’s reasonable to assume there is a leak. A clogged vent or damaged fill tube is another common problem that could cause the toilet bowl to lose water.

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How Does a Toilet Work?

Before troubleshooting your toilet, you should understand how it works. 

A toilet works by operating through a series of steps that work in unison. The flush handle is attached to an arm inside the tank. When the user pushes down the handle, it raises a flapper.

The raised toilet flapper then releases water from the tank into the toilet bowl. The water flushes the waste through the trap and into the drain and sewer lines. As the water level decreases in the tank, a float drops, which opens the fill valve. 

Water returns to the tank through the fill valve. The water level rises until the float reaches the point that closes the fill valve.

How to Determine the Cause of Your Toilet Bowl Losing Water

Step 1: Run Your Faucets

Make sure your toilet is full first, then run your sink and tub faucet. 

Step 2: Listen For Gurgling

If your drains are drawing air through your toilet, you should be able to hear a gurgling noise as air passes. Determine if you heard a gurgling noise or not. If you did hear gurgling, the vent is likely damaged. If not, continue to step three.

Step 3: Turn All Faucets Off

Turn all the faucets off, and do not use any water until you test the toilet. 

Step 4: Test the Toilet

Refill the toilet. Make sure it’s at its full level and mark the location. Wait an hour or so, then look at the water level. If the water level is lower and you haven’t used any other drains, there is leaking through a small crack.

Reasons Why Your Toilet Bowl Slowly Loses Water

If your toilet bowl is slowly using water, it can result in higher energy and utility costs. It also can take a toll on your plumbing systems. A small leak in the toilet can result in 200 gallons of water loss each day. 

There are several reasons that your toilet bowl is slowly losing water.

A Cracked Toilet Bowl

If you determine that your toilet bowl has a crack, you will need to replace it. 

Replacing a toilet is relatively simple. Turn the water shutoff valve clockwise until it stops, then flush the toilet until the water stops. Dry any remaining water from the tank and bowl. 

Next, remove the waterline and tank by unscrewing the water hose from the bottom of the tank. Remove the nuts on the bottom of the tank that connect it to the toilet bowl. Lift the tank off the bowl, then remove the bowl.

On each side of the toilet, there will be a nut holding it to the ground. Remove these, then lift the toilet up. Remove any caulking that is holding it down. 

Install your new toilet in the reverse of these steps. Don’t forget to replace the wax seal between the toilet and the flange on the ground to prevent leaking. If you have trouble lifting heavy objects, you might want to ask a buddy for help.

Clogged Vent

If you have a clogged vent, you will need to go to the roof of your home and clear any obstructions. To do this, remove any caps or debris blocking the vent, then open it. Use a garden hose to spray water directly down the opening to clear any blockage. 

If the vent begins to overflow, the blockage is not clear, and you’ll have to continue troubleshooting the vent. Feed an auger into the vent and rotate it clockwise until you reach a tough spot. Continue doing this to break up any debris until the water drains.

Once the water has drained, spray the water down again to see if it drains quickly. If it does, reassemble the vent by putting any caps back on. If you still suspect a clogged vent, try to remove the debris again, then contact a plumber. 

Water Level Set Too Low

If your water level is set too low, you will need to adjust it. To change the water level, adjust the valve on the intake pipe using a screwdriver. Turn the adjustment screw on the valve clockwise to increase the water level.

Damaged Fill Tube

A damaged fill tube is one of the most common reasons the toilet bowl water level is low. The fill tube is a small, flexible plastic hose that is typically black or clear. It connects to a wider vertical tube called the overflow tube inside the toilet tank.

The fill tube allows water to flow into the toilet bowl every time the toilet is flushed. Over time, the fill tube can unclip from the overflow tube or become damaged. When this happens, the toilet tank fills with water, and the valve shuts off the water flow before the toilet fills. 

To determine if there’s a damaged fill tube, lift the tank lid and visually inspect the tube. If it has shifted but it’s still in good condition, reconnect the overflow tube.

Other Common Toilet Bowl Issues

Many things can go wrong inside of your toilet. Here are some of the most common toilet issues that you should know about to be prepared.

Toilet Is Leaking

Does your toilet leak when you flush? Toilet leaks can come from a multitude of places. The supply pipe, the bottom of the toilet bowl, inside the bowl, or at the supply valve, to name a few. 

You may notice a pool of water around your toilet or if your water bill is increasing every month. If that’s the case, there’s likely a toilet leak.

Toilet Tank Is Constantly Dripping

The toilet tank will fill up with water after flushing. If you hear a constant dripping sound after the tank is full, there may be a leak somewhere. The leak could be in the line or the system.

Finding the root of this problem can be complicated, so sometimes it’s best to contact a professional first. 

Toilet Flushing Causes Backup in Sink or Tub

If you hear gurgling sounds in the tub or sink after you flush, you probably have a clogged vent pipe. This could be a partial clog or a full clog, but you can’t use at-home tools to analyze this. Contact a professional to fix the issue.

Toilet Flushes by Itself

When your toilet begins to flush by itself, it can be alarming. This happens when water leaks from the toilet tank into the toilet bowl. If this occurs, it can waste up to 200 gallons of water a day. 

Test your toilet for tank leaks by dropping food coloring into the tank water. Avoid using the toilet for about 30 minutes, then check the water in the toilet bowl. If there are any signs of food coloring, you’ve identified the source of the problem. 

The solution is a quick fix. Simply replace the rubber flapper in your tank.

Toilet Keeps Running After Flush

If your toilet continues to run after you flush, the flapper valve in the toilet is likely not appropriately sealed. Check inside the tank to make sure nothing is blocking the valve from closing. Then, remove any mineral buildup that could be on the valve seat. 

After you’ve done that, make sure that the pull chain is at the right length and not holding the valve open. If this does not solve the problem, contact a plumber as repairing a flush valve can be tricky. 

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Related Questions

Why is my toilet bowl sweating?

Your toilet is a natural dehumidifier. Moisture forms on the tank’s surface when the tank water is colder than the surrounding air temperature. The difference in temperature causes the toilet to sweat. 

You have two options to stop your toilet from sweating. You can dry out the air in the bathroom using an air conditioner or dehumidifier. Another option is to install an anti-sweat valve in the water supply line leading to the toilet.

Why is my toilet bowl making a gurgling noise?

When your toilet makes a gurgling noise, this indicates there is negative air pressure built up in the drain line. The negative air pressure eventually releases and pushes the air backward through the drain pipe and into the toilet bowl. This creates a gurgling noise, and the water in the bowl may flush itself.

The buildup of negative air pressure results from a clog in the drain system or your home’s vent stack. Depending on the severity of the issue, you can sometimes remedy the clog yourself. However, if the culprit is a collapsed sewer line, it should be fixed by a professional sooner than later.

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Stacy Randall

Stacy Randall is a wife, mother, and freelance writer from NOLA that has always had a love for DIY projects, home organization, and making spaces beautiful. Together with her husband, she has been spending the last several years lovingly renovating her grandparent’s former home, making it their own and learning a lot about life along the way.

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