Parts of a Toilet: How They Work and Common Fixes

By Amanda Lutz | January 22, 2024

A woman's hand pressing down on the handle of a white toilet bowl inside of a modern bathroom.

A toilet that breaks down requires urgent attention, whether the problem stems from a small clog or a major leak. The many parts of a toilet can make it challenging to diagnose the origin of a breakdown. We’ll walk you through the parts of a toilet and explain how a toilet works in the guide below. We’ll also offer tips to help you fix common toilet problems.

Toilet Tank

The tank is the upper part of your toilet, which holds around two gallons of water. The tank supplies fixed amounts of water to the bowl to make a siphon effect that washes away waste. The tank’s purpose might seem straightforward, but it’s a critical part of the toilet’s intricate system. Here are the main toilet tank parts:

Fill Valve and Float

The toilet fill valve is a plastic tube that connects to the water supply line and refills the toilet tank with water after a flush. When you flush the toilet, the fill valve opens and allows water to flow into the tank.

Fill valves in newer toilets are equipped with pressure-detecting mechanisms that sense when a tank is adequately filled. Older toilets have floats, which trigger the valve to close when the water level rises to a sufficient level.

Fill valves can wear out over time, which slows tanks’ refill processes. A worn-out valve may lose the ability to close properly, which will cause water to continue flowing into the tank.


When you press the toilet handle or push its button, you activate the toilet’s chain, which raises the toilet’s flapper and allows water to flow from the tank into the bowl. Once you release the handle, the flapper covers the opening and stops the water flow to allow the bowl to fill back up. 

You may encounter physical damage to a handle, or you may need to tighten it to ensure proper flushing.

Overflow Tube

The overflow tube is a vertical plastic tube that prevents water from overflowing the tank and flooding the bathroom. Overflow tubes direct excess water from the tank into the bowl if pressure-sensing mechanisms malfunction.

The overflow tube can crack over time, and mineral deposits may prevent tubes from working properly. 

Toilet Chain and Lift Wire

A toilet chain (also called a lift wire or lift chain) connects the handle to the flapper valve. When you press the toilet’s handle or push its button, the chain lifts the flapper valve and allows the water to rush from the tank into the bowl. Once you release the handle, the chain or wire reverts back to its original position and lowers the flapper.

A chain that is too short, too tight, or too loose may disrupt the toilet’s flushing functions.

Toilet Flapper

The toilet flapper seals the opening between the tank and the bowl. When you press the handle, this rubber or plastic valve rises and allows the water to flow from the tank to the bowl. Once the tank is empty, the flapper returns to its resting position and closes the opening tightly. 

Flappers wear out over time and can become hotbeds of mold and bacteria growth. This frequently stops them from functioning correctly.

Water Supply Line

A water supply line is a stainless steel flex pipe that delivers fresh water from your home’s main water line to the toilet tank. The line usually includes a manual shut-off handle in case of a toilet breakdown.

The most common problems with water supply lines are loose fittings or loose shut-off valves. High water pressure can cause the line to burst in rare cases.

Toilet Bowl

The bowl is the lower part of the toilet. Its primary function is to receive and hold waste until the flushing process begins. The bowl is curved, is finished with a special coating that facilitates cleaning, and includes a water-filled trap, which creates a seal to prevent odors from escaping. 

The main parts of the toilet bowl are the following:


The bowl is the porcelain base of the toilet that’s attached to the floor. It’s equipped with a seating element for the user.

Bowls rarely malfunction, but flange bolts that secure the bowl may come loose and cause the structure to move or leak.

O-Ring Seal

The O-ring seal is a rubber ring located between the toilet bowl and the toilet tank. Seals prevent water from seeping through the bottom part of the tank.

An O-ring that is improperly placed during toilet installation may not stop water from leaking out of the tank. This part may also wear out or crack over time.

Wax Seal and Floor Flange

Wax seals and floor flanges collectively secure the toilet bowl to the floor and keep the bowl connected to the drainage system. Wax seals line the flange and help prevent water from leaking out of the bowl. Floor flanges are metal rings that attach to the floor.

An improperly installed flange or an old wax seal can frequently lead to water waste.

Fixing Common Toilet Issues

A toilet performs its function 10 to 15 times a day in an average household, and even the best and most expensive materials break down over time. Not every issue requires professional assistance, though. Consider DIY remedies for the following problems:

Constantly Running Toilet

A running toilet is one of the most common and annoying problems that homeowners face. Below are typical causes:

Most hardware stores have all the spare parts you need to fix a running toilet. When you’re ready to make repairs, open the tank lid, remove the old part, bring it to the store with you, and buy the necessary replacement part.

Toilet Leaking

A running toilet only affects your water bill, but a leaking toilet can damage your home. The most common reasons for a leaky toilet include the following:

You can fix a leaking toilet by replacing faulty parts or tightening loose elements. Shut off the water supply to the toilet before starting repairs.

Toilet Filling Slowly

A toilet that fills too slowly can be a headache. This problem could be caused by the following:

Check the shut-off mechanism on the water supply line, and ensure it’s fully open. Open the tank, and examine the float and overflow tube. If they seem damaged or displaced, replace them. Low water pressure in the plumbing system or improperly installed water supply lines can also cause a toilet to fill too slowly. If you notice either issue, it may be best to call a professional plumber.

Toilet Flushing Incorrectly

A toilet that doesn’t complete a flush isn’t performing its function properly. The main reasons for this include the following: 

To fix an incorrectly flushing toilet, remove the tank cover and examine the toilet’s internal components. If you notice signs of wear and tear on any parts, replace them. If mineral buildup is to blame for flushing issues, you need to clean the tank. A water softener system installation can prevent this issue in the future.

Our Recommendation

Toilets are built to last, but frequent use leads to wear and tear even if you take excellent care of your toilet. Familiarizing yourself with the parts of a toilet and their functions can prepare you to fix most problems. Remember that most toilet issues are the result of worn-out parts, and you can buy replacements at most home improvement stores. Consider calling a repair professional if you encounter significant issues such as water supply problems or clogged main lines.

Parts of a Toilet FAQ

What are the inside mechanics of a toilet?

The inside mechanics of a toilet include a chain, flapper, fill valve, float, overflow tube, and several seals. These parts work together to facilitate flushing, control water flow, and maintain proper water levels in the tank.

What is a toilet flange?

A toilet flange is a metal component that connects the bottom of the toilet bowl to the drainage system and the floor.

What does a toilet tank do?

A toilet tank holds water that’s necessary to flush the toilet. There is a mechanism inside the tank that controls water flow and release.

What are the different types of toilet seats?

The different types of toilet seats include closed-front seats, open-front seats, soft-close seats, and seats with features such as heating or nightlights.

What part of my toilet keeps running?

The part of your toilet that keeps running is likely the flapper, fill valve, or overflow tube. Water can run uncontrollably if these parts are damaged or worn out.