How to Replace a Faucet Cartridge: Step-by-Step for Plumbing Professionals

If a bathroom or kitchen faucet is leaking, most probably there is a problem with the faucet cartridge. 

Most household faucets are cartridge faucets. The faucet cartridge is a piece of plastic in the faucet that controls the flow of water. Faucet leaks are often caused by worn cartridges or rubber O-rings. 

This article discusses how to replace faucet cartridges and prevent leaks and drips. 

What is a Faucet Cartridge?

A faucet cartridge is a cylindrical valve assembly seated inside the faucet body. It controls both water volume and mix temperature. When you turn the handle, the cartridge shifts internal ports to increase or restrict flow.

There are three main cartridge types in the commercial and residential supplies:

1. Ceramic disc is ideal for high-traffic commercial faucets and rated for 500,000 cycles. 
2. Brass or metal is durable under high pressure. These metals are common in industrial and outdoor fixtures. 
3. Composite or polymer is a cost-effective option for light-duty residential installations. 

What are the Signs that a Cartridge Needs Replacement?

To replace a shower or faucet cartridge, you must first recognize the signs of failure. Act quickly when you spot these indicators to prevent water damage and avoid emergency plumbing calls:

• Persistent drips or leaks even when the faucet is fully closed. 
• There is loss of temperature control characterized by cold water entering the hot outlet, or vice versa. 
• There is reduced flow rate from the spout. This is often caused by internal cartridge wear or mineral scale. 
• The handle cannot be turned or is unstable. 
• Vibration or noise is heard during operation. 
• There are visible cracks, pitting, or mineral deposits on the cartridge body. 

The faucet’s cartridge can last from 15 to 20 years. But, in facilities with hard water (above 200 ppm calcium carbonate), expect a shorter service life. To ensure proper maintenance, schedule inspections every 10 years. 

How to Replace Faucet Cartridge 

How do you change a cartridge in a faucet? Before learning the steps, it is important that you have all the necessary tools on hand. 

Tools You Need

NOTE: Before disassembling each part, photograph each stage. This helps in reassembly and serves as training reference for junior technicians. 

Here is a list of the necessary tools: 

• Adjustable wrench;
• Phillips and flathead screwdrivers;
• Hex key or Allen wrench set (1/8″ and 3/16″ cover most faucet brands);
• Needle-nose pliers or water pump pliers;
• OEM-matched replacement cartridge;
• Silicone-based plumber’s grease;
• Clean cloth or rag;
• Cartridge puller (optional: needed for press-fit installations).

(Alt text: How do you change a cartridge in a faucet? Here is a diagram that shows how to replace a faucet cartridge.)

Step 1: Close the Water Supply

First, close the shut-off valve beneath the sink by turning it clockwise until fully seated. Next, open both faucet handles to drain residual line pressure. Lastly, plug the drain to contain small hardware.

Step 2: Remove the Handle

First, remove any decorative cap at the top or front of the handle. Then, remove the retaining screw using the correct Phillips or Allen key. Finally, pull the handle straight up and set it aside.

Step 3: Access and Extract the Cartridge

First, unscrew the escutcheon nut or bonnet nut using an adjustable wrench. Next, locate the retaining clip; it is a horseshoe-shaped brass piece. Remove it with needle-nose pliers.

Now, take note of the cartridge orientation before removal. Grip the cartridge stem and pull it straight out. Use a cartridge puller if it resists. 

Step 4: Install the New Cartridge

First, check if the replacement matches the original by brand, model number, and body diameter. Next, coat the O-rings and the insertion shaft with silicone grease. Never use petroleum-based lubricants because they degrade rubber seals within 12 months.

Then, align the cartridge notches with the faucet body slots. For single-handle units, confirm hot and cold port orientation before seating.

Finally, press the cartridge fully into the valve body. Reinstall the retaining clip.

Step 5: Reassemble

First, thread the bonnet nut by hand first, then tighten with an adjustable wrench. Avoid overtightening because it cracks polymer cartridge bodies.

Finally,  reattach the handle, insert the retaining screw, and replace the decorative cap.

Step 6: Test

First, slowly open the shut-off valve. Watch the supply connection for drips.

Next, run each tap separately. Check the pressure, temperature control, and shut-off function. If the hot and cold supply are reversed on a single-handed faucet, this may be port misalignment. You can correct this by removing the cartridge and rotating it 180°.

How to Replace a Shower Cartridge

The process on how to replace a shower cartridge follows the same sequence. There are just two key differences in access. 

Step 1: Shut off Water Supply

Shower valves lack a local shut-off. Instead of just shutting off the water supply from the valve, close the main supply valve for the building zone.

Step 2: Remove the Shower Parts

Remove the shower trim plate (escutcheon) by unscrewing the fasteners behind the handle. This exposes the cartridge housing inside the wall cavity.

Step 3: Reinstall the Shower Parts

In standard commercial showers (per ASSE 1016), pressure-balancing cartridges include a pressure-sensing piston. Before replacing, check if the replacement part carries the same ASSE 1016 rating as the original. Using a non-rated part voids the valve warranty and creates a scald risk. 

Step 4: Test the Shower

After reassembly, test temperature response by cycling from cold to hot and back. Balanced valves should hold outlet temperature within ±3°F (±1.7°C) during supply fluctuations. Knowing how to install a shower cartridge correctly the first time avoids re-entry callbacks.

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Case Study: Replacing Faucet Cartridge in Multi-Unit Residential Complex with 180 Bathrooms

Scenario:

A property management group overseeing a 180-unit apartment complex in the Pacific Northwest contacted AIM Faucet after experiencing repeat leak callbacks. 

Problem

Technicians were replacing entire faucet units on each callback. The average replacement cost is $210 per unit, which includes parts plus 45 minutes of labor. The facility was spending over $2,900 a month on reactive repairs. 

Issue

An on-site inspection identified ceramic disc cartridge wear as the primary failure mode. Hard water in the region (measured at 280 ppm CaCO₃) had accelerated mineral scaling inside the cartridge seat. This degraded the seal surface. The faucet bodies and finish remained structurally sound.

Solution

The facility transitioned to a scheduled cartridge replacement program using AIM Faucet OEM-compatible ceramic cartridges. Technicians received a one-page replacement protocol based on the steps in this guide. All 180 units were serviced over three weekends.

Result

This resulted in a decrease in monthly service callbacks from 14 to under 2. The part cost per repair also decreased from $85 (full faucet) to $18 (cartridge only). The estimated 12-month savings reached $27,400 in combined parts and labor. 

Conclusion

If you want to know how to install a shower cartridge or how to replace a shower cartridge, you should be equipped with the right knowledge and tools. 

Before replacing a faucet cartridge, you should also learn to identify signs of wear that indicate cartridge replacement. After diagnosing the issue, make sure that the replacement parts are compatible with the original. 

At AIM Faucet we produce OEM-compatible faucets and replacement cartridges for contractors, distributors, and facility management companies around the world.

We test every AIM Faucet cartridge for 500,000 cycles to ensure they last. The ISO 9001:2015 certified manufacturing process guarantees the compliance with the NSF/ANSI 61 and 372 requirements for potable water. In addition, all our WaterSense certified faucet cartridges meet the EPA flow rate requirement of 1.5 gallons per minute or less. Export footprint covers North America, Europe, and Southeast Asia.