A bathtub consists of three functional systems: the tub body that holds water, the supply system that delivers it, and the drain/overflow system that removes it safely.
Standing in the plumbing aisle staring at overflow plates, waste tees, and drain shoes gets confusing fast. The terminology matters because ordering the wrong part means another trip to the store. Here is every bathtub part you will encounter, divided by where it lives and what it does, with the names you actually need to know.
The Main Tub Body And Its Visible Parts
The tub itself is called the tub body, shell, or basin — the water-holding structure. The top edge is the rim, also called the lip or ledge. On alcove tubs (the kind set against three walls), the front exterior panel is the apron or skirt. These shape terms help you identify your tub type before buying any replacement parts.
Water arrives through the faucet or spout, controlled by one or two handles. A single-handle setup uses a cartridge inside the valve body behind the wall to mix hot and cold. Two-handle setups give you separate hot and cold valves. Many tubs also include a shower diverter — a button or lift lever on the spout that redirects water to the shower head. The diverter is not the same part as the valve cartridge; if the spout leaks while the handles are off, the diverter mechanism is likely the issue, not the cartridge.
Drain And Overflow System: What You See And What You Don’t
Two visible openings handle drainage. The overflow plate sits high on the tub wall with an opening beneath it — this prevents overfilling by letting excess water escape before it reaches the rim. Never call this the “drain cover”; that is a separate part. The actual drain sits at the bottom of the tub and includes the drain flange (the visible metal or plastic ring) and the stopper, which can be a pop-up, push-and-pull, or simple lift-and-lock mechanism.
Behind the wall and under the tub, the hidden plumbing does the real work. The overflow connects to an overflow elbow and a pipe that ties into the waste tee — the fitting where the overflow and the bottom drain meet. From the drain, the drain shoe (or waste arm) carries water to the P-trap, that curved pipe section that traps sewer gases. All of this hardware together is called the waste-and-overflow assembly, and its layout depends on your tub type. Alcove tubs typically use a wall-mounted overflow plate with the under-tub drain shoe and waste tee arrangement; freestanding tubs use different geometry.
Optional Features That Change What You Are Working With
Not every tub has jets, grab bars, or a headrest. Whirlpool and air bath systems add jets, pumps, and control panels — these require specialized parts and service. Grab bars are safety devices needing secure structural mounting into wall studs, not decorative accessories. Some tubs include an access panel (often in an adjoining closet or wall) for servicing the plumbing without tearing out tile.
If you are replacing parts on your own tub, our roundup of the best bathtub parts covers the most reliable replacement kits and components available today.
The table below summarizes the main parts by system for quick reference when you are shopping or troubleshooting.
| System | Visible Parts | Hidden Parts |
|---|---|---|
| Tub Body | Shell/basin, rim/ledge, apron/skirt | Tub support (mortar bed or frame) |
| Water Supply | Faucet/spout, handles, diverter, shower head | Valve body, cartridge, supply lines |
| Drain System | Drain flange, stopper, overflow plate | Overflow elbow, waste tee, drain shoe, P-trap |
| Optional | Jets, grab bars, headrest, access panel | Pump, air blower, control module |
Common Naming Differences You Should Know
Some names are regional or informal. “Rim” and “ledge” mean the same thing. “Apron” and “skirt” are interchangeable for the front panel of an alcove tub. “Drain shoe” and “waste arm” both describe the pipe section between the bottom drain and the P-trap. Using the wrong term at a hardware store may get you the wrong part, but knowing the alternatives helps. The names “spout diverter,” “valve,” and “cartridge” are not interchangeable — a diverter redirects water, a cartridge controls mixing, and the valve body is the housing behind the wall.
Freestanding tubs, alcove tubs, and whirlpool tubs use different part layouts and different waste-and-overflow assemblies. Measure your existing parts before ordering replacements rather than relying on tub type alone.
FAQs
What is the difference between the overflow plate and the drain cover?
The overflow plate sits high on the tub wall and prevents overfilling by allowing excess water to escape. The drain cover (drain flange) sits at the bottom and is the visible part of the main drain. They are separate components serving different purposes.
Can I replace a tub spout diverter without replacing the valve cartridge?
Yes, because they are separate parts. The spout diverter is the mechanism inside the spout that redirects water to the shower head. The valve cartridge controls temperature and flow and sits behind the handle. A leaking spout usually means a bad diverter, not a bad cartridge.
Do all bathtubs have a P-trap?
Every tub connected to a home’s drain system requires a P-trap. It is the curved pipe section that holds water to block sewer gases from entering the room. The P-trap is always hidden beneath the tub or behind an access panel and is part of the waste-and-overflow assembly.
References & Sources
- Family Handyman. “Parts of a Bathtub: A Complete Guide.” Covers visible and hidden tub components with diagrams.
- Angi. “The Parts of a Bathtub Explained.” Breaks down drain, supply, and tub body terminology for homeowners.
- Badeloft USA. “Bathtub Parts Every Homeowner Should Know.” Illustrated guide to tub components and common naming variations.