Understanding the Parts of a Toilet

parts of the toilet illustration

Illustration: The Spruce / Theresa Chiechi

Toilets address a need that’s basic, human, and ordinary, and they do so with elegant simplicity. In the last century or so, minor aspects of the toilet have evolved, but the basic parts of a toilet remain the same.

At the base is a bowl that the user sits on. The toilet tank, a separate piece that’s attached to the bowl upon installation, collects water from the home’s water source. Upon demand, the tank sends all of that water rushing into the bowl to carry waste materials into the sewer.

Understanding the parts of a toilet is vital to diagnosing and fixing common toilet issues such as clogs, a constantly running toilet, or leaks around the tank or bowl.

Toilet Bowl

The toilet bowl is the large base on which the user sits. With an oblong or round hole to accept waste, most toilet bowls are made of vitreous china, a waterproof material that resists staining well.

Built into the bowl is a C-shaped internal trap that carries the waste away. The trap’s other function is to keep a small reserve of fresh water as a seal against sewer gases escaping into the home.


Using a toilet plunger is sufficient to force most toilet clogs down into the sewer line and away. When that doesn’t work, a toilet auger can be used to pull the clog in the opposite direction—upward and out.

Tank O-Ring Seal

The tank o-ring seal (more commonly known as a mack washer), or tank-to-bowl gasket, is a large O-shaped rubber or wax washer or gasket that fits between the bottom of the toilet tank and the top of the toilet bowl. Its purpose is to prevent water from leaking out of the toilet tank.

When a toilet is leaking below the tank yet above the bowl, the reason is usually a poorly installed or cracked O-ring seal. The solution is to empty the tank of water, remove the tank, and replace the O-ring with a new one.

Floor Flange

A floor flange is a round metal or plastic bracket located above the sewer pipe protruding from the floor and below the toilet bowl. The floor flange, or closet flange, is firmly attached to the floor by screws or bolts. The toilet attaches to the flange with T-bolts.

Subjected to leaking water, floor flanges can become rusty and break, leaving the toilet shaky and prone to leaks. If a toilet is leaking at the bottom, usually the cause is a broken floor flange, a poor wax seal, or both. The fix is to remove the toilet, remove and replace the flange, and set the toilet back in place.

Wax Seal

A wax seal is a round, cone-shaped gasket that fits between the bottom of the toilet bowl and the top of the floor flange. Its purpose is to prevent water from leaking from the toilet. Wax seals can be used only once.

If a toilet is leaking at the base, the wax seal may be cracked or insufficiently sized for the space. To fix, remove the toilet, scrape off the old wax ring and dispose of it, then replace it with a new wax ring or a silicone ring.


Extra-thick wax rings are available that help to provide a tighter seal, especially when there are height issues with the floor.

Toilet Tank

The toilet tank is the upper part of the toilet which rests on the top of the toilet bowl. The toilet tank contains the water that gets released when the toilet is flushed. The toilet handle is attached to the toilet tank.

Toilet tanks are solid-state pieces made of porcelain. With no moving parts, they rarely malfunction. Sometimes, a toilet tank may crack or break. Hairline cracks in toilet tanks can be repaired by drying out the inside of the tank and adding silicone plumbing epoxy to the crack.


The toilet handle is the lever located on the toilet tank that is used to flush the toilet. In some cases, the handle is not a lever but a large button on the top of the toilet lid. Dual flush toilets have two buttons: one for flushing liquid waste and another for flushing solid waste.

The toilet handle is attached to a long arm that extends into the toilet tank. The end of the arm pulls the chain that releases the flapper.

It is rare for the toilet handle itself to malfunction, but the arm inside the toilet tank can bend or break from repeated use. It is possible to bend metal arms so that they are straight again. Bent or broken plastic arms must be replaced. The handle and the arm are one piece, so both must be replaced together.


The toilet float is a round plastic or aluminum ball that is buoyant enough to float on top of the water in the toilet tank. The toilet float is responsible for managing the level of the water in the toilet tank.

When toilet floats no longer float on the tank water, the best solution is to install a new float. Symptoms that point to the need for a new toilet float: water flowing after the tank is full; tank not filling completely; or the toilet continually running.


The toilet chain, sometimes called a lift chain, is a short strip of metal-linked chain that connects the toilet lever to the toilet flapper. After the toilet lever is depressed, it pulls the toilet chain, which in turn lifts the toilet flapper.

Since toilet chains receive a lot of use, they often break. If the chain breaks off at either end, it often can be reattached using a piece of wire. Better yet, purchase a new chain. Chains come as part of a flapper repair kit or a toilet refill repair kit.


The toilet flapper is the rubber stopper located on the inside base of the toilet tank which lifts and closes to send water into the toilet bowl. The toilet flapper is controlled by the toilet lever via the chain. After the water has been released, the flapper falls back into place and closes the hole at the base of the tank, much like a rubber stopper in a bathtub.

The toilet flapper can harden and lose its seal after enough use. This is often one reason for constantly leaking toilets. New toilet flappers can be purchased independently and installed on a one-for-one basis. Sometimes, they come as part of a toilet refill repair kit, including a toilet fill valve, related hardware, and the toilet flapper.

Refill Tube

The refill tube is a flexible plastic tube in the center of the toilet tank that trickles water into the toilet bowl when the toilet is refilling. Toilets must have a small amount of water standing at the bottom of the toilet bowl as a trap that seals the bathroom against sewer gases.

Plastic refill tubes may crack and leak over time. A solution is to purchase a refill tube repair kit and install that in place of the faulty refill tube.

Water Supply Shut-off Valve

A water supply shut-off valve is an oblong-shaped knob on the flexible braided water supply line. The water supply line comes from the home's fresh water supply and attaches to the bottom of the toilet tank. The purpose of the shut-off valve is to turn off the water to the tank in case of emergency or for repairs.

Shut-off valves often have plastic handles, so they are prone to breakage if turned too tightly. Shut-off valves can be removed and inexpensively replaced. The same braided water supply line can be reused if it is still in good condition.