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Faucet Cartridge Fundamentals

tip If you need to replace either the hot or cold water cartridge for one of your faucets, we recommend replacing both cartridges at the same time. This will save you time, money, labor cost, inconvenience, frustration, and hassle.

There are a variety of cartridges which vary in their structure and function.

What is a Faucet Cartridge?

A faucet cartridge is a device within a faucet that controls the flow of water.

What is the Function of a Cartridge?

The function of a cartridge is to turn the water on and off, and to control the quantity of water flowing through a faucet.

How Cartridges Work

Many faucet cartridges are integrated within valves, which provide the structural support from within which the cartridge can perform its water regulation function.

A cartridge is connected to a handle and resides within a valve, which resides within the faucet. When you turn the handle of a faucet, the handle turns the cartridge within the valve to control the flow of water out of the spout of the faucet.

Types of Faucet Cartridges

Water Volume Control Cartridges (Quarter Turn Ceramic Disk Cartridges)

Volume control cartridges turn the water on and off, and control the quantity of water flowing through a faucet.

Volume Control Cartridges

Hot and Cold Water Mixing Cartridges (Thermostatic Cartridges)

Thermostatic cartridges are part of mixing valves that mix hot and cold water to achieve a desired water temperature. They also prevent very hot water from scalding your skin.

Thermostatic Cartridges

Anatomy of Ceramic Disk Cartridge

Hot Versus Cold Cartridges

A hot ceramic disk cartridge is the same as a cold ceramic disk cartridge, except that it opens in the opposite direction.

A hot cartridge opens or turns on the water by moving in the counter-clockwise direction. A cold cartridge opens or turns on the water by moving in the clockwise direction.

1/2" Versus 3/4" 20 Point Cartridge

16 Point Versus 20 Point Cartridges

Two types of quarter-turn ceramic disk cartridges are very common: 16 point cartridge and 20 point cartridge. These differ in the shape, size, and number of ridges or splines in the stem of the cartridge. These must be compatible with the number of splines in the faucet handle.

What Happens to Cartridges Over Time?

A cartridge is like a spark plug of a car engine. It lasts years but eventually needs to be changed.

Over time, faucet cartridges experience wear and tear, corrosion, and become coated with mineral deposits. This results in improper functioning such as water leaks and difficulty in turning the handles.

New Cartridge

Used Cartridges

New Thermostatic Cartridge

Used Thermostatic Cartridge



Common Indicators That You Should Replace a Hot or Cold Volume Control Cartridge

If your faucet is more than several years old and you are experiencing any of the following symptoms, you most likely need to replace one or both of the cartridges.

  • Water leaks when handle is in off position
  • Faucet handle is difficult to turn

Should You Replace One Cartridge or Both the Hot and Cold Cartridges?

If you need to replace either the hot or cold water cartridge for one of your faucets, we recommend that you replace both cartridges at the same time, because the other cartridge may also need to be replaced in the near future.

Faucet cartridges last years but eventually need to be changed, because over time they experience wear and tear, corrosion, and become coated with hard water mineral deposits. This results in improper functioning such as water leaks and difficulty in turning the handles.

Replacing both cartridges at the same time will save you time, money, labor cost, inconvenience, frustration, and hassle in the future. We offer a bundle of the hot and cold cartridges that costs less than buying both cartridges separately. Also, the bundle qualifies for free shipping, so you save even more.

Quarter Turn Ceramic Disk Cartridges


Common Indicators That You Should Replace a Thermostatic Cartridge

If you have a thermostatic shower system which is more than several years old and you are experiencing any of the following symptoms, you most likely need to replace the thermostatic mixing cartridge.

  • Proper water temperature is not maintained
  • Water temperature fluctuates while using shower
  • Water is not hot enough (turning the water temperature lever to maximum does not yield hotter water)

Thermostatic Cartridges




How to Replace Cartridges

Replacing Cartridge on Faucet with Cross Handle
Using a Socket Wrench to Remove a Cartridge

Highly recommended tool: 17mm socket with long handle.

Replacing Cartridge on Concealed 1/2" Thermostatic Valve Assembly

Highly recommended tool: 17mm socket with long handle.

Replacing Cartridge on Exposed 1/2" Thermostatic Valve Assembly

Highly recommended tool: 17mm socket with long handle.