When a toilet breaks down, you must repair it immediately. Leaving a damaged toilet unrepaired can result in water damage, clogged pipes, and numerous other problems that will only worsen over time. But, it can be difficult to diagnose what is broken inside a toilet when it’s not functioning properly. Looking inside a toilet tank reveals a complex assortment of moving parts, all of which can cause a slew of problems when it breaks.

Knowing how toilets work and what each part does is essential for recognizing when a problem warrants a professional. A broken handle arm or flapper seal is an easy fix, but a malfunctioning fill or flush valve is a bit trickier and may require the skills of a pro. This guide is your one-stop shop for understanding all the parts of a toilet tank, explaining what each piece does, and rating how easy each is to repair.

a diagram of the parts of a toilet tank
Image Source: Today’s Homeowner Team / Sam Wasson


The tank is the large, lidded cistern that holds the toilet water and mechanisms needed for flushing. Depending on the make of the tank, it may be attached to the wall above the lid (called a two-piece toilet) or directly to the bowl. The difficulty in repairing a damaged toilet tank will depend on the extent and nature of the damage. Small hairline cracks are easy to fix, requiring only a few minutes of work and silicone caulking. But holes, large cracks, or detachment from the wall typically require the aid of a plumber.

Tank Lid

The lid is the large, heavy cover that sits atop the toilet tank. On a dual flush toilet, it will have a small button in the center of the lid that acts as a secondary flushing mechanism. Unfortunately, due to the weight and size of most tank lids, repairs are difficult and typically not worth the effort. In most cases, it’s recommended that you purchase a replacement directly from the manufacturer.

Flush Lever and Toilet Handle

The flush handle is located outside the tank and connects to the inner handle arm, lift chain, and flapper or flush valve. By pushing down on the handle, the arm raises, lifting the flapper via the chain, initiating the flush. This three-piece flushing mechanism is one of the most common parts of a toilet to break and is, thankfully, easy to repair. Small toilet repair kits are sold at big-box and home repair shops that include all parts of the flush lever assembly, making repair jobs a breeze.

Handle Arm

The handle arm is the thin plastic or metal arm that connects the handle to the chain and flapper. Handle arms made from plastic can be prone to bending, breaking, or coming loose and will typically need replacing. Unfortunately, most arms and handles are a single piece, so you’ll need to replace the entire mechanism if one breaks.

Lift Chain

The chain is the final piece of the flush-lever-and-handle mechanism, connecting them to the flapper or flush valve. While it’s rare for these chains to break, they’re extremely easy to mismeasure when determining the appropriate length. If the chain is too short, it will not allow the flapper to close fully, leading to constant running. If too long, the chain can get sucked down under the flapper blocking it and keeping the seal from forming.

Toilet Flush Valve and Flapper

a toilet flush handle being used
Image Source: Canva

The flush valve is the toilet part responsible for sending a large amount of water from the tank into the bowl, creating a flush. Flush valves are connected to the overflow tube and flapper. When the toilet is flushed, water funnels from the tank, through the flush valve, into the bowl.

Flush valves come in two categories, canister valves and flapper valves. If your toilet is older, it likely has a flapper valve – in these, the flapper connects to the flush valve, with the chain pulling directly on the flapper. Newer toilets, especially those made by Kohler, employ canister valves. These valves sit in the middle of the tank, with a rubber seal at the bottom (an integrated flapper) with the chain pulling on the entire canister.

Repairing a flush valve can either be extremely easy and inexpensive or difficult and costly, depending on the type you have. Flapper valves are simple and cheap to repair with a kit from a home improvement store. Canister valves, however, are typically challenging and expensive to replace.

Toilet Flapper

The flapper, also known as the flapper valve, is the large rubber stopper located at the bottom of the toilet tank. It’s connected to the flush valve and contains a valve seal (sometimes called a gasket) which creates an airtight seal between the flapper valve and the toilet tank. The flapper and gasket are prone to faults as they slowly become more hard and rigid, losing their seal over time. Thankfully, replacing the valve and gasket is relatively easy, with handy DIY kits being sold that can provide everything you need to make a full repair.

Toilet Fill Valve

Also called a ballcock valve, this component is responsible for refilling the toilet tank with water after it has been flushed. Fill valves connect to the water supply line, refill tube, and float. Fill valves are topped with a cap that contains a float adjustment screw. While fill valves are more difficult to replace than a flapper or flush lever, it’s still doable at home with some tools and the right replacement parts, taking about an hour to complete.

Refill Tube

This part of the toilet tank connects the fill valve to the overflow tube and serves several purposes. First, it helps prevent the tank from overflowing by diverting excess water into the overflow tube. Second, it controls the water flow from the fill valve and sends it to the overflow tube, which fills the toilet tank. Without a properly functioning refill tube, your bowl would have too much or too little water on each refill, leading to numerous problems. Refill tubes are prone to faults, becoming cracked or clogged over time. If you notice your tank taking too long to fill or not filling by the correct amount, you may have a bad refill tube.

Refill tubes are simple to fix and typically come included in kits for repairing fill valves or overflow tubes, but you can also purchase them separately.

a toilet tank with a complex flush system
Image Source: Canva


A float is a buoyant device used to determine when the tank is full of water. Floats are either attached directly to the fill valve or connected through a float arm. As its name suggests, the float sits atop the water and activates the fill valve as the water level recedes. Older style models are called float balls and resemble baseball-size rubber spheres, while more modern ones are usually small plastic cylinders. Floats, even modern models, are extremely easy to install and replace, typically taking under two hours.

Overflow Tube

The overflow tube has two functions: One, to divert excess water out of the tank, and two, to direct water from the refill tube into the toilet bowl. It connects directly to the flush valve and is fed from the top via the refill tube. Overflow tubes don’t typically break, but clogs can be common, especially if you have hard water with large amounts of sediment. When this happens, they’re a medium-difficulty repair job for DIY-minded homeowners, requiring a little work, know-how, and the right tools.

O-Ring Seal

Also known as a “mack washer,” tank-o-ring seal, or tank-to-bowl gasket, this is a large “O” shaped rubber or wax ring that separates the tank from the toilet bowl. It prevents water from leaking from the tank onto the toilet seat and surrounding area. While repairing an o-ring seal is technically easy, you must remove the entire tank by unscrewing the connecting toilet bolts. This process can require a decent amount of upper body strength and coordination, making it difficult for some homeowners.

Final Tip on Toilet Repair and Toilet Tank Parts

the main water valve of a toilet, sitting behind the bowl
Image Source: Canva

While toilet leaks can be nerve-wracking when they pop up, you can easily and quickly repair most faults. When dealing with a damaged and running toilet, remember that the water shutoff valve is your best friend. If your toilet is leaking water, no matter the cause, turning off the system’s supply will always be the best first step. Furthermore, just about every repair job you can do on a toilet tank requires it to be empty of water anyway, so by turning off the main valve right away, you can save time later on. Even if you’re planning on calling a plumber, you’ll still want the water shut off while waiting for them to arrive.

You can typically find the main water valve behind the bowl at the base of the toilet, connected to the wall and the tank via the toilet flange.

Editorial Contributors
Sam Wasson

Sam Wasson

Staff Writer

Sam Wasson graduated from the University of Utah with a degree in Film and Media Arts with an Emphasis in Entertainment Arts and Engineering. Sam brings over four years of content writing and media production experience to the Today’s Homeowner content team. He specializes in the pest control, landscaping, and moving categories. Sam aims to answer homeowners’ difficult questions by providing well-researched, accurate, transparent, and entertaining content to Today’s Homeowner readers.

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Lora Novak

Senior Editor

Lora Novak meticulously proofreads and edits all commercial content for Today’s Homeowner to guarantee that it contains the most up-to-date information. Lora brings over 12 years of writing, editing, and digital marketing expertise. She’s worked on thousands of articles related to heating, air conditioning, ventilation, roofing, plumbing, lawn/garden, pest control, insurance, and other general homeownership topics.

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