Toilet Basics: Understanding the Different Components

Wide angle shot from above of a white toilet and blue tiles.

Whether you're remodeling an entire bathroom, installing a new toilet, or just trying to stop an annoying runny tank, it's good to know the basics of the parts of a toilet, how they work and how you can fix them without calling a plumber.

Standard Toilet

White and almond are most common colors. Made of vitreous china and finished with a high-gloss glaze. the toilet is designed to be durable and sanitary. Federal law mandates that all new toilets use no more than 1.6-gallons per flush, compared to old models that used 3.5-gallons or more. Gravity-fed toilets operate with a conventional flush, where water draining from the tank is released into the bowl and its weight and gravity pull waste down the drain.

Pressure-assisted units use pressure built up within the water supply to increase the force of the flush. These tend to be noisier than gravity-fed models, but the bowl empties quickly (within 4 seconds). The larger water seal surface results in fewer stains. Since the trapway on pressure-assisted models has fewer bends, it is less likely to clog than a gravity-fed system.

A third type of toilet uses a pump to assist the flushing operation with increased pressure. Some models are even designed to flush automatically when the seat lid is closed. Dual flushers feature a lever that uses 1.6-gallons for solid waste removal and 1.1-gallons for liquid waste.

The rough-in is the distance from the finished wall to the center of the sewer outlet. Standard rough-ins are 10, 12 or 14-inches. Another style is the one-piece toilet

Flush Handle

The flush handle activates the flush valve ball. They are usually sold in combination with the trip lever. It attaches with a left-handed screw, which screws on in a counter-clockwise direction. This prevents it from accidentally unscrewing during use.

Flush Valve Seat

Located at the bottom of the tank, the flush valve seat surrounds the opening that lets water into the bowl. It's kept closed by a rubber flush ball or flapper. The flush valve seat is attached to the Overflow Tube, which drains water back into the bowl if the water level goes above it. This is a good safety precaution if the inlet valve fails.

Flapper Valve Seat Ball

Also called a Flush Valve Seat Ball, this device sits on the flush valve seat and attaches to the trip lever with a chain, rod or guide arm. When the outside handle on the toilet tank is pressed down, it raises a trip lever that pulls the flapper off its seat. Water inside the tank pours through the opening to flush the toilet bowl.

The valve stays closed with water pressure; however, once the trip lever lifts the device, it remains off the seat by floating on top of the water until the tank is empty. As the water level drops, the flapper gradually settles back into the opening, sealing it so the tank can refill for the next flush. A new style design has replaced the older ball-style. It is connected to the float arm with a chain and eliminates many of the problems associated with wires, rods and guide arms


Also known as a fill valve or inlet valve, the ballcock controls refilling the tank. It consists of multiple parts but is commonly sold as a complete unit. Parts include: upper lever, float rod, lower lever, plunger, valve seat, refill tube, nylon seat, eye screw, body, hush tube, regular shank, shank gasket, lock nut, coupling nut washer, riser pipe and repair shank.

Older models use a float ball. When repairing them it is best to replace the entire unit instead of trying to repair its parts. Newer models eliminate the flat ball and may have an anti-siphon feature that keeps toilet water from backing up into the water lines.

Float Ball

Part of the Ballcock, when the water level raises the float ball it shuts off the valve that lets water into the tank. Made of plastic or copper, it should be replaced if it develops cracks or corrodes and let water inside.

Tank-to-Bowl Hardware

This hardware creates a secure connection between the tank and the bowl. It consists of long brass bolts with rubber washers and a large foam-rubber washer. One size fits all toilets.

Bowl Gasket

Also known as a wax ring, the bowl gasket seals the joint between the toilet bowl and the drain piping in the floor. Some types have a plastic ring inside to add protection. For a better seal, use two rings, one on top of the other.

Closet Flange Bolt

The closet flange bolt secures the toilet bolt base to the floor flange.

AC Toilet Water Supply

This connects water supply to toilet. Flexible types are easiest to install.

Toilet Seat

Toilet seats are made of plastic or kiln-dried hardwood. Hardware should be sturdy and non-rusting. Metal hardware should be solid brass with a quality finish. Some toilet seats have easy-on, easy-off hinge posts that facilitate installation by the homeowner. These hinge posts also make it practical to remove the seat for thorough cleaning.

Toilets Safety Tips

Use an anti-siphon ballcock to prevent toilet water from backing up into the water lines. Don't over-tighten the bolts that connect the closet flange bolts or the tank to bowl hardware. The porcelain can crack, which means you'll have to replace the entire tank or bowl. In areas prone to earthquakes, do not use the rigid water supply tubes. Rigid water lines cannot move. If they are forced to move they can become disconnected and cause serious water damage

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