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The Difference Between a Shower Valve and a Shower Cartridge

The shower valve and cartridge are the central part of any shower system. Shower valves are connected to the hot and cold lines of the home and direct the flow of water to the faucet. Shower cartridges are a component within the shower valve that regulates the pressure and temperature of the water.

Here we will explain further what these components are, how they work, and when they need to be replaced.

What is a shower valve?

A shower valve is a rough in component that manages, mixes, and may divert the flow of water. Shower valves are a one-time installation, typically when the home is built, and will last for decades. There are many different types of shower valves.

What is a shower cartridge?

Within a shower valve rests the shower cartridge. This component contains an assortment of pins, seals, and gaskets that regulates temperature in the event of sudden changes in water pressure. Shower cartridges, within a pressure balancing valve, prevent the shower water from becoming too hot or too cold when the water pressure changes, typically when a toilet is flushed, or a faucet is turned on. The cartridge is often replaced once every few years.

How to replace a shower cartridge

To replace a shower cartridge, you’ll need to remove the escutcheon plate and handle. Then you’ll want to remove the old cartridge and match the model number and replace it with a new cartridge. Replacement should take roughly 30 minutes. If you are not comfortable with the task, a plumber can replace the cartridge for you.


Here is a rough estimate of the cost to replace either a shower valve or cartridge:

  • Shower valve: $50-$100 for parts, $400-$600 for labor (total: $450-$700)
  • Shower cartridge: $20-$50 for parts, $100-$200 for labor (total: $120-$250)

Note: Shower valves require the wall to be opened, which is why the installation is typically done during initial construction or remodeling.

How do the shower valve and cartridge work together?

Before water enters the cartridge, it is pressure balanced by a piston in the body of the shower valve. This prevents drastic changes in temperature. Here is a video demonstrating that process:

As you pull on the shower handle, water enters the cartridge and mixes. The cartridge then regulates the temperature and allows it to flow through the showerhead.

What is a shower diverter?

Managing the flow or direction of water is the shower divert valve. These are separate components to allow the shower to be used as a shower head or a tub spout. There are three types of shower diverters:

  • Single Diverter Valve: This is a single on/off diverter. The stem you pull up on your tub faucet or a button you press on the escutcheon plate is a single diverter.
  • Two Valve Diverter: Where there is a single handle that gradually diverts the water from the tub spout to the shower head. It is paired with a single handle to control flow and temperature.
  • Three Valve Diverter: Is a separate knob that rests between the hot and cold water lines (three knobs in total) that directs the water to either the tub spout or the shower head.

Some diverters may contain their own cartridge that regulates the temperature. This is commonly found on a three-valve diverter.

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Frank Harmenstein

From humble beginnings as a plumber and handyman, Frank Harmenstein has emerged as a leading authority on shower heads, a title he has earned through years of dedication and hard work. With over two decades of experience in the plumbing industry, Frank has developed an unrivalled expertise in the installation, maintenance, and repair of shower systems. His passion for shower heads has led him to write extensively on the subject, sharing his knowledge and insights with readers around the world.

Born and raised in a small town, Frank's interest in plumbing was sparked at an early age by his father, who was a respected plumber in their community. Inspired by his father's dedication to his craft, Frank pursued an apprenticeship in plumbing and soon discovered his niche in the world of shower heads. He quickly gained a reputation as a skilled handyman who could fix any shower-related issue and provide expert advice on selecting the perfect shower head for any bathroom.

After years of honing his skills and knowledge, Frank decided to share his passion for shower heads with a wider audience by becoming an author.