How to Adjust the Anti-Scald Valve on Your Shower

Unexpected temperature changes in the shower often come down to one small but important part: the anti-scald valve. Understanding how these valves work, when it’s time to install a new one, and how to adjust it as needed can help you keep your water at a safe and comfortable temperature.

What Is an Anti-Scald Valve?

An anti-scald valve, also called a tempering valve or pressure-balance valve, is a plumbing device that helps regulate your shower water temperature. It automatically adjusts the mix of hot and cold water to maintain a steady temperature, even if someone flushes the toilet or runs a faucet elsewhere in the house.

These valves are commonly built into single-handle shower controls, but can be installed as separate fixtures if needed. In most setups, the anti-scald shower valve is behind the trim plate or inside the shower handle. It’s usually a notched disc or a screw-like piece. Some plumbing systems have similar temperature-regulating valves near the water heater, but those are less common for individual fixtures like showers.

When to Adjust an Anti-Scald Valve

If your shower water suddenly changes temperature or won’t get hot enough, you may need to adjust your current one or install a new anti-scald valve. Common reasons to adjust it or install a new one include:

• Your shower doesn’t already have an anti-scald valve
• The current valve is worn out, stuck, or leaking
• Water stays lukewarm or fluctuates during use
• You’re remodeling or updating an older system
• A plumber recently worked on the fixture
• You need to meet modern plumbing safety codes

Installing a new valve typically requires a plumber, but making small adjustments is usually a DIY task.

How to Adjust the Anti-Scald Shower Valve

Installing a new anti-scald shower valve typically means removing the old valve and inserting a compatible thermostatic or pressure-balancing model behind the trim. It’s best to have a licensed professional install the valve, especially when specialized plumbing or tile work may be involved. Once the valve is in place, you can usually do the anti-scald valve adjustment yourself with a few basic tools.

Before you begin: Turn off the water supply and check your owner’s manual for brand-specific steps or precautions.

Step by Step:

1. Take Off the Handle and Trim Plate

Use a screwdriver or Allen wrench to remove the shower handle. Behind it, you’ll find the trim plate, which you can carefully remove to see the valve.

2. Find the Anti-Scald Shower Valve

Look for a gear-like disc or notched ring near the cartridge. This is the adjustment control. Some models have a small screw instead.

3. Make the Adjustment

Gently turn the control to change the maximum hot water setting:

• Turn clockwise to lower the temperature
• Turn counterclockwise to raise it

4. Reassemble and Test

Put everything back together, turn the water on, and test the temperature. You may need to repeat the process once or twice to get the temperature right.

Related: Got a leaky faucet? Follow the steps in our guide.

Tips for Safe Anti-Scald Valve Adjustments

• Make small changes. A little turn goes a long way.
• After adjusting, use a thermometer to test the water before stepping in.
• Don’t raise the temperature above 120°F to reduce burn risk.

Most valves are preset to about 110°F, so aim for a max temperature of around 115°F to 120°F. If you're still noticing temperature swings or can't get enough hot water, it might be time to call a plumber to check if the valve was installed correctly.

Maintenance Tips for Anti-Scald Valves

Once your anti-scald valve is set up and working, it doesn’t need much upkeep. But a little maintenance can help it last longer and work better. Over time, things like mineral deposits or worn parts can affect how well it controls your water temperature.

Here are a few simple ways to keep it in good shape:

• Wipe down the shower handle area regularly to keep it free of grime.
• If you have hard water, check the valve yearly for buildup.
• After major plumbing work or water heater changes, test the temperature again.
• If your water starts fluctuating or won’t stay warm, it may be time to clean or replace the valve.

These quick checks can help your valve stay reliable and keep your showers more comfortable.

Do All Faucets Have Anti-Scald Valves?

Not every faucet or shower includes an anti-scald valve. Most newer single-handle setups have one built in, but older systems and showers with separate hot and cold knobs often don’t. These dual-knob setups mix water farther down the line, so the valve can’t react to sudden pressure changes.

If your water temperature shifts when someone flushes a toilet or uses another tap, your shower likely doesn't have an anti-scald valve. In that case, you may want to consider having one installed.

How a First American Home Warranty Helps

When you are dealing with a plumbing issue in your home and you have a First American home warranty, you simply make a service request. Depending on your plan, coverage may include repairing or replacing some parts of your plumbing system that wear out over time. We’re here to help you with repairs or replacements when something goes wrong with all your covered systems and appliances. Plans vary, so review your coverage or call our team with questions.

Need help staying ahead of unexpected repairs? Get a free quote today.

The contents of this article are provided for general guidance only. First American Home Warranty does not assume any responsibility for losses or damages as a result of using this information.

Please be aware that if you disassemble a covered system or item, it can invalidate your home warranty or manufacturer's warranty.