The brass tacks of bathtub plumbing
Bathtub plumbing systems are very intricate and important.
Your bathtub’s piping system is designed to bring clean water to your home and remove dirty wastewater.
Simple bathtub plumbing repairs might be DIY-friendly, but calling in a pro is always a better idea.
Your bathtub’s plumbing is complex and highly important—its efficiency is critical to your personal hygiene, and keeping it in tip-top shape will help prevent leaks and other plumbing emergencies. Learning about all the different parts of your bathtub plumbing system is useful when you need to replace something, call in a repair, or just have stronger working knowledge of your home’s most essential appliances.
Your bathtub’s water supply pipes pull water from your home’s main water line to your bathtub. Your bathtub has two supply pipes—one for hot water and one for cold water—which are connected to a diverter pipe, allowing both lines to come through a single spout. Connected to the hot water line is a cartridge valve, which allows you to control the temperature of your bathtub’s water.
The drain you find at the bottom of your bathtub is known as the wastewater drain—it’s usually below the spout. There are three components to this drain:
Stopper: This plugs the drainpipe so you can fill or drain your tub. It also stops items from falling into the drain and potentially clogging the pipe.
Waste outlet: This pulls wastewater into the sewer.
Traps (or P-traps) are curved sections of pipe located beneath sinks, showers, and bathtubs. They hold a small amount of water that creates a seal, preventing sewer gasses from entering your home’s water supply line.
The tub overflow drain does exactly what it sounds like—it prevents flooding in the event that your bathtub overflows. It is usually located on the side of the tub, below the spout. The drain has a faceplate, which is a metal cylinder, and an overflow pipe that connects to the faceplate and diverts excess water to the pipes behind the main drain rather than onto your bathroom floor.
This four-cross pipe connects your water supply, diverter pipe, and drain, allowing water to run from your home’s plumbing system to the different parts of your bathtub.
Your bathtub might not have a shower, but shower attachments are becoming increasingly common; bath-shower combinations are great for those with kids or pets. Here are the main plumbing components that make up a shower:
Showerhead: This is where water comes out when you turn your shower on. Showerheads can be attached to the wall or connected with a flexible hose or sliding bar.
Shower control: Sometimes called a diverter valve or shower handle, the shower control is installed between the showerhead and the water supply. It allows you to switch the water’s flow between the bathtub, shower, or—if applicable—hand shower.
Diverter pipe: This pipe sends water from your bathtub spout to the showerhead.
Shower valve: The shower valve lives behind the shower control—like the cartridge valve, it controls the temperature. More expensive valves are pressure-balanced and can prevent extreme temperature changes.
Your bathtub also has an emergency shutoff valve. These valves are hidden behind an access panel, which can be located in the bathroom, a room behind the bathroom, or the ceiling of the floor below the bathroom. The valve can be used to shut off water to your bathtub emergency, in case of a serious flood or overflow.
To keep your bathtub—and, more broadly, your bathroom—plumbing in excellent shape, you’ll want to be on the lookout for signs of a leak so you can prevent water damage. You might have a plumbing leak if you notice any of the following:
Noticeably higher water bills
Visible mold or mildew around the bathtub
Musty-smelling bathroom
Stained or damaged ceilings, floors, or walls
If you see any of the above, have a local plumber come by to check things out. Generally speaking, it’s wise to go through a general plumbing inspection checklist every year to look for anything that might be amiss with your plumbing system.
Finally, place a drain catch over the stopper to prevent hair and other debris from getting into the drain, which can lead to a clog.
If you need to make a repair to your bathroom plumbing, you can try to handle it yourself or call in a professional plumber near you. If the solution is as simple as replacing a visible part, it’s possible that a DIY fix can be done without much of a headache. If you’re worried about a pipe behind the wall or suspect a leak, however, it is wise to call in an expert who can do a thorough inspection and get to the root of the issue. On average, the cost of a plumbing repair is around $300.
The water supply lines run underneath the bathtub. These two pipes deliver cold and hot water to the bathtub—the cold water comes from the main water supply, and the hot water comes from the water heater. The pipes are made from copper, cream-colored plastic CPVC, or red and blue PEX tubing.
A bathtub diverter is used when you have a shower-tub combination. The diverter valve allows you to send the water to either your tub faucet or your showerhead. Diverter shower valves cost between $20 and $200. Higher end brands, such as Moen, might cost more—some models are over $250.
The overflow drain and wastewater drain connect to the same main pipe to take water away from your bathtub. Your overflow drain is meant to prevent damage to your bathroom—especially the floor around your bathtub, where excess water can quickly create a mold or mildew problem.
