How to tell if your shower mixing valve is bad?

Author: Kaleb Funk  |  Last update: Thursday, October 2, 2025

If you've noticed water dripping or leaking from your shower mixing valve, this is a clear sign that something is wrong. In most cases, this problem is caused by a faulty valve stem, which can become worn or damaged over time.

How do you know if your shower mixing valve is bad?

Inconsistent water temperature in your shower can be frustrating and uncomfortable. If you notice that the water temperature fluctuates between hot and cold, it could be a sign of a malfunctioning shower valve. A faulty valve can prevent the correct mixing of hot and cold water.

How do you know if the shower valve needs to be replaced?

A leaky or dripping shower head indicates a faulty shower valve. The inner rubber seals of the shower valve wear out with time and fail to create a proper seal for effectively holding the water when the shower is shut off. Besides the rubber seal, worn-out O rings and rubber gaskets can also cause shower valve leaks.

How do you test a mixing valve?

First, you need to check the temperature of the blended water. Then, detach the cold water supply from the thermostatic mixing valve. Wait five seconds and check if the water temperature is under 39 degrees Celsius. If you don't notice any considerable changes, the thermostatic mixing valve is working correctly.

Can mixing valves go bad?

If the mixing valve isn't functioning correctly, it can cause many problems with your water heater. For example, a stuck hot water heater mixing valve may cause water to become too hot, leading to the tank overheating and potentially bursting.

Mixer shower problems: 4 most common mixer shower faults + repair tips.

Can a shower mixing valve get clogged?

If your water pressure in your shower does not feel as though it's as powerful and/or increasing your hot water doesn't improve the situation, you may have a clogged hot water mixing valve.

When should I replace my mixing valve?

Sudden temperature swings in the shower aren't enjoyable. If you've ever been shocked by scalding or cold water, then it may be time to swap out that mixer valve for a pressure-balancing or thermostatic alternative. An old or damaged valve may also stick, making it difficult to turn the water on or off.

What is the life expectancy of a mixing valve?

The life expectancy of a thermostatic mixing valve can vary based on usage and water quality but typically ranges from 5 to 10 years. Regular maintenance and cleaning can help extend its lifespan.

Why is there no cold water from my shower mixing valve?

A valve may have been accidentally turned off. Hopefully, you can just turn the shut-off valve back on and be good to go. If this isn't the problem, you should call a professional. If the other faucets around the house do have cold water, then the problem is most likely the pressure-balancing valve.

How much does a new mixing valve cost?

The cost to replace your shower valve depends on the type you need. Here are the five most common ones with cost estimates. Mixing valve: Mixing valves combine hot and cold water so you can adjust the temperature and cost $40–$350.

Do I need a plumber to replace a shower valve?

If your shower valve is damaged beyond repair, you may need to replace it to prevent leaks. Removing your old valve and installing a new one can take time, but with patience, a novice handyman can do it without the help of a plumber.

Can you replace a shower mixing valve?

A faulty shower mixing valve can lead to frustrating temperature and pressure issues, turning your relaxing shower into an unpleasant experience. Fortunately, replacing a shower mixing valve is a manageable DIY repair.

Why do shower valves fail?

Signs of Shower Valve Problems

Wear and tear from everyday use, lime and dirt buildup in your water supply, and making changes to your hot water source can all lead to issues with your valve.

Why is my mixer shower not working properly?

The usual suspects for this problem are a blocked shower head, kinked or damaged shower hose, or blocked inlet filters in the shower itself. It could also be due to faulty non-return valves. Permanently running either hot or cold.

How do you clean a mixing valve?

The best thing is to shut off the water and disassemble the valve as much as you can, cleaning the parts with vinegar or a commercial decalcifying agent. Get as much solvent as you can into the inner workings of the valve turning the mixing valve mechanism back and forth to loosen debris.

Can a shower mixing valve go bad?

Shower valves don't last forever, and regular use will eventually cause your shower valve to stop working. Valve seals can wear out and cause leaks over time. The valve's bearings can wear down, impacting valve function and causing unexpected temperature changes.

Why is there no cold water coming out of my mixer tap?

Check the Shutoff Valve

A common reason for not getting cold water is that the shutoff valve for the cold side could be partially or fully closed. If this valve isn't open all the way, it can block off that refreshing cold water you're waiting for.

How do you fix a clogged shower mixing valve?

Soak the cartridge in white vinegar for an hour. Remove and rinse thoroughly with water. While the cartridge is soaking, turn on your shower to flush the opening. We recommend opening the cold water side of the valve to avoid contact with hot water.

How do you tell if a mixing valve is bad?

3 Signs Your Thermostatic Mixing Valve Has a Problem
  1. Your water temperature isn't right. If a TMV valve stops working correctly, then you may notice that your hot water suddenly starts to run hotter than it should. ...
  2. Your water doesn't flow normally. ...
  3. You have leaks or drips.

How long do shower mixers last?

Mixer showers are one of the most reliable types of showers, and they can operate problem-free for a little over four years for those designed for residential use. Some types of thermostatic valves can last between 10-15 years when you purchase better-quality brands.

Do plumbing valves go bad?

Signs of damage or wear on shut off valves include rust or corrosion of the valve body. It can also be sticking or broken handles and gushing water when it is closed. Rusting can occur over time and cause corrosion of the valve body. It's also a sign of an old or defective valve that needs immediate replacement.

Can I replace a mixing valve myself?

If you can solder a copper pipe, you should be able to install a pressure-balancing mixing valve yourself. A decent-quality valve will cost about $125. The most difficult aspect of this project will be gaining access to the old valve inside the wall.

How much does it cost to replace a shower mixing valve?

Shower mixing valve replacement cost

Replacing a shower mixing valve costs $225 to $575 on average for materials and labor.

Can you replace a shower mixer yourself?

You might be wondering if it's possible to fit a new thermostatic mixer shower yourself. While it may not be a straightforward DIY task, if you have some knowledge of showers and plumbing, you may be able to tackle this task yourself.

Previous article
What is the warning on the Magic Eraser?
Next article
Is the power company responsible for the line to my house?