Hot And Cold Water Not Mixing In Shower [Why+ How To Fix] (2024)

Beyond any doubt, a soothing and consistent water temperature is the key factor of an enjoyable shower experience. But what if the shower valve is refusing to blend hot and cold water as it should. Don’t worry you are not alone in the row of encountering such a frustrating and uncomfortable bathing experience.

The underlying reasons why the hot and cold water not mixing in shower include:

• Faulty thermostatic shower mixing valve
• Incorrect adjustment or blocked pressure balancing shower valve
• Low water pressure
• Malfunctioning water heater
• Clogged shower inlet filters
• Or due to using a broken shower lever

Before considering anything else, inspect the mixing valve to verify whether it is positioned correctly. If not, adjust it or replace the bad shower valve.

Keep on reading till the end of your guide to explore all the effective & easiest ways to troubleshoot this issue by yourself.

Possible Reasons & Solutions For Hot And Cold Water Not Mixing In Shower [Quick Overview]

From my own experience, I’ve discovered that a few particular issues lead to water mixing issues in your shower.

Before getting into details, let’s make your further reading easier through this quick table below, highlighting all the potential reasons for this issue with the quick solutions:

Why Isn’t Hot And Cold Water Mixing In My Shower [Easy Solutions]

Here are the most common reasons for the issue when your shower not mixing hot and cold water with the effective fixes:

1. Blocked Shower Inlet Filters

If the hot and cold water not mixing properly in your shower, the best chances are the inlet filter of your shower valve is blocked or not working properly. Even it is the obvious factor to blame if you have an exposed bath shower mixer.

The main purpose of this shower filter is to filter out impurities and contaminants from the water before it reaches the showerhead.

Over time, the filter becomes clogged with sediment or hard mineral contents, reducing the flow of water to the shower. Even if it would be a common phenomenon for you if you are living in a hard water heater containing high mineral content like calcium and magnesium.

As the water passes through the filter, the minerals start accumulating in the filter screen and reduce the normal water flow.

When the normal water flow is restricted, it makes it challenging for the shower’s temperature control mechanism to regulate and maintain the water temperature as your set temperature.

Don’t hassle me! A quick cleaning will be enough in this instance to help you get back to a comfortable water temperature.

How To Fix:

As for the first step, turn off the water supply to your shower system. Use a hex key and remove the handle from your shower faucet. Then remove the temperature stop ring from its position and set it aside.

Then unscrew the shower hose from the valve body and remove the shower valve from the wall using an adjustable spanner. Now you can easily get access to the inlet filters.

Take out the filter and soak it in warm water to remove loose debris and sediments. Then gently scrub them with a small brush and rinse with clean water thoroughly.

Once the filter is clean and free of debris, reattach it back to the valve connection and re-fix the valve on the wall again. Turn on the water supply now and verify the water temperature.

2. Old & Faulty Shower Lever

A faulty shower lever is another major factor for why it becomes so difficult for you to maintain the shower temperature just right. It would be like when you are turning on the right faucet, you’re blasted with cold water. And with one touch to the left of the faucet, you are getting scalding hot water.

In such a situation, a malfunctioning or old shower lever is one of the major culprits to blame. When your double-handle shower faucet isn’t working properly, it makes it challenging to maintain a consistent water temperature in the shower.

The best possibility is the connection between the faucet handle and the valve stem wears down with age, resulting in the handle becoming too loose. This leads to difficulty in adjusting the water temperature accurately.

The accumulation of mineral deposits within the shower handle is another reason that affects its ability to move smoothly. Thus when you are turning or adjusting the handle, it fails to work properly and causes an uneven mixing of hot and cold water.

How To Fix:

Before doing anything, first off make sure you’ve turned off the water supply to your shower. Now examine the shower lever for any visible signs of damage, wear, or corrosion. As best chances are it is loosened from its connection. Look for screws or bolts securing the handle, and tighten them properly.

In case you find the handle secured with a set screw, use the Allen wrench to tighten it.

If the handle is still loose after tightening the fasteners, you can apply the plumber’s tape to create a snug fit. [Be careful not to over-tighten them, as this can cause damage]

Once the handle is secured in its place, turn on the water supply and whether you are getting water at the appropriate temperature. If not, you might be dealing with a deteriorated shower handle that needs replacement.

3. Low Water Pressure

Lack of water pressure is another major reason to blame why your shower is failing to mix hot and cold water properly. Adequate water pressure is key for accurately mixing the hot and cold water in the shower valve.

If the water pressure is low either from hot or cold inlet, it will cause inconsistent water temperature.

In the case of the shower mixing valve, you will find three inlets connected to the water supply line. Two inlets are for hot and cold water, as well as a third inlet for a balanced or “mixed” water supply.

The water pressure should be equal for both hot and cold water, otherwise, the mixing valve won’t function properly.

Now, several factors are contributing to low water pressure in the shower. Let’s have a short glimpse at all the potential causes with effective fixes!

i) Partially Closed Water Shut-off valve

The first possibility is the water shut-off valve for your bathroom fixture is not fully opened or partially closed. In many shower systems, there are typically two water shut-off valves, one for hot water and one for cold water.

In order to ensure the full stream of hot water and cold water to mix the shower, it is crucial to fully open both shut-off valves.

So for the first step, head over to the cold and hot water shut-off valves and turn the lever to the fully open position.

In most cases, shut-off valves become stiff or hard to turn over time due to corrosion or mineral deposits. Plus, older shut-off valves may also have broken levers or detached from the connection., For instance, you may need to replace the damaged valve.

ii) Blockage In The Water Supply Line

After turning on the water shut-off valve, you will need to inspect the water supply, leading to your shower for any signs of clogs and blockages. It is the common factor that contributes to issues with hot and cold water not mixing properly in a shower.

Blockages in the water supply line restrict the flow of water and the volume of hot and cold water reaching the shower mixing valve. When the water flow is limited, it is obvious that the valve will fail to mix the two water temperatures accurately.

How To Fix:

Inspect the hot and cold water supply lines to your shower for any stuck debris or sediment. It would be accumulated with mineral deposits as well. However, use a flexible wire, a plumber’s snake, or a pipe brush to remove the obstruction.

In case of severe mineral deposits, contact a professional to deal with the issue.

iii) Leakage In The Water Pipe

If the above two factors have already been ruled out, another best possibility is you have a leakage in the water pipe. Yes, you got it right!

When there is leakage in the water supply line due to wear and tear, it can cause water to escape the plumbing system. That results in reduced water flow and highly affects the mixing of hot and cold water within the shower valve.

How To Fix:

Inspect the water supply for any signs of damage. If there is a minor leak in the water pipe, you can easily repair it by yourself using a pipe repair clamp. But make sure you’re choosing the right clamp that matches the size of your pipe. You can even use a compression fitting for smaller leaks or pinhole leaks.

In case the damage is beyond repair, it’d be better if you could contact a professional; plumber for better assistance.

4. Faulty Pressure-balancing Shower Mixing Valve

Beyond any doubt, dealing with inconsistent water temperatures due to improper mixing of hot and cold water is the worst way to start your day. For instance, if you have a shower valve with a pressure balancing spool, it would lead to such an inconvenient shower experience in case it malfunctions.

A pressure balancing valve is an essential plumbing device that is designed to maintain a balanced water pressure between the hot and cold water supplies. Though it does not actually sense the temperature of the water, it adjusts the flow of hot and cold water to achieve a balanced flow.

But in case the valve isn’t adjusted or calibrated correctly during installation, it will fail to adjust the water stream in the proper ratio. Besides, over time, mineral deposits, sediments, or debris from the water supply accumulate in the valve’s internal components, preventing the hot and cold water from mixing effectively.

At times, you may find the valve’s internal parts become damaged or worn, affecting its normal functionality.

Whatever the fact is, you can easily address these issues by following some pro tips and tricks discussed in the below section:

How To Fix:

As for the first step, turn off the water supply to your shower. Unscrew the fasteners and screws holding the shower handle in place. Remove the shower handle and cover plate to get access to the pressure-balancing shower valve cartridge.

First, check whether it is adjusted as per the manufacturer’s instructions. If not, adjust it by turning the adjustment knob or limit stop to your desired temperature until you achieve the desired temperature.

Like older standard shower valves, the pressure-balancing shower valve has an inner cartridge that may wear out and eventually go bad. For instance, you will need to replace the bad cartridge with a new one.

Once a new cartridge is installed in the shower valve, it should work like new.

5. Malfunctioning Thermostatic Shower Mixing Valve

If your shower is not mixing the water temperature properly, it is sure that you will get water either too hot or too cold. In such a situation, the wrong adjustment of the thermostatic mixing valve is one of the root culprits to blame here.

The thermostatic mixing valve or TMV works by mixing cold water with outgoing hot water so that the hot water that leaves the fixtures is at a safe temperature level. These are called whole-house anti-scald valves as they ensure water at a safe temperature is delivered to the faucets in the home.

But in case of a faulty or malfunctioning mixing valve, it will fail to sense the water temperature and blend the hot and cold water properly. That results in either scalding hot water or icy water.

There are several factors attributed to the malfunctioning shower mixing valve:

i) The Mixing Valve Is Not Set Correctly

If there is any temperature malfunction from your shower water,the best possibility is the valve is not adjusted as it should be.It is essential to calibrate the mixing valve correctly to allow it to mix the hot water and cold water in an appropriate ratio to achieve the set water temperature.

While working with pipe, most of the time users accidentally flipped the positions of the mixing valve. So as for the first step, you will need to inspect the adjustment of the mixing valve and adjust it accordingly.

Here is all how you will do so:

• Locate the mixing valve of your shower system. Here you will find a handle or cover over the valve assembly.
• Simply unscrew the cover and get access to the adjustment knob.
• Take a socket wrench and adjust the knob to your desired temperature setting.
• After making the adjustments, turn on the water supply to your shower and verify whether it is mixing the hot and cold water correctly.

ii) Clogged TMV

Blockage in the mixing valve is the major factor that restricts to mixing of the hot and cold water streams properly. As mentioned above there are a few inlets in the mixing valve. Over time, hard mineral content from water can easily accumulate in the passages and openings within the valve.

Whenever hard water is heated, lime-scale deposits on moving parts and piping in general.

Besides, sediment present in the water can also create clogs in the valve that reduce the water flow and affect the proper functioning of the valve.

How To Fix:

In this step, you will need to inspect the mixing valve for any clogs. If so, disconnect the water supply lines connected to the valve.

When done, take out the valve and start cleaning. Once you get the mixing valve out of the shower connection, start cleaning! Take a small container and pour white vinegar into it. Then mix it with water in an accurate ratio.

Now soak the mixing valve into the vinegar solution, making sure it is submerged fully.

Allow it to soak for several hours or even overnight. This will help to dissolve the lime-scale deposits in the valve body.

After that time, use a small bush and gently scrub the valve, especially in areas with visible deposits. When done, rinse it thoroughly under running water to remove any remaining vinegar and debris.

iii) Busted Mixing Valve

The major reason why your shower does not mix hot and cold water would be the busted mixing valve. Due to long use, the rubber part of the valve may get worn out. At times, the defective mixing valve is the culprit itself that causes this issue.

For instance, replacing the bad valve is the only solution to help you get rid of this issue. Don’t worry! You can easily replace your bad mixing valve by following the effective processes discussed in our comprehensive guide.

In case you are not skilled enough in plumbing work, we recommend to head to a professional plumber to complete the replacement tasks for you.

6. Plumbing Crossover

If still you are struggling to get the desired temperature from your shower, another best possibility is you are dealing with a plumbing crossover issue with your shower mixing valve. If you have recently installed the mixing valve in your shower, chances are hoses are installed backward.

As earlier mentioned, there are up to three water inlets in a mixing valve. One is for the hot water stream and one is for the cold water stream. Another one is used to mix the two streams to produce water at the set temperature.

As per the manufacturer’s recommendation, it really does matter on which side the hot and cold water are installed. In case the hoses are installed revered, it is obvious it fail to mix the hot and cold water as it should.

How To Fix:

To address this problem, you will just have to switch the hoses back to their correct positions. For instance:

Turn off the water supply to the shower before making any changes. Now inspect the mixing valve water supply connections to see whether they are at their right position. Typically, the hot water supply will be connected to the left side of the valve, and the cold water supply to the right side.

However, you can easily identify it by the specific labeling on the valve body. It would be “H” signaling the hot water side and “C” for the cold water side.

In case, the hoses of your shower valve are reversed, simply switch the hoses back to the right position. If required, seek professional help for better assistance.

7. Failing Water Heater

It is also possible that you are experiencing a hot water issue with your mixing valve caused by any of the problems with your water heater.

This is more likely related to your tankless or tank water heater if it is cycling on and off rather than providing a continuous hot water stream.

If that is so, a similar problem would occur with the taps served by the same water heater. Anyway, there are several factors that contribute to your water heater is turning off randomly:

• Degradation in power supply (electric model)
• Insufficient fuel supply (gas model)
• Low water flow
• Using too many hot water fixtures at a time
• Worn-out heating elements
• Or due to plugged-up heat exchangers.

How To Fix:

Start by inspecting the fuel supply to your gas-operated water heater. Inspect the LP tank for fuel amount and refill it if needed. Also, check for gas pressure in the unit and adjust it.

If you have an electric model, make sure you have any loose or damaged wiring connections. Reset the tripped circuit breaker or replace the blown fuse. Besides, verify the operation of the heating element. If required, replace the non-functioning heating elements.

In the case of the gas-operated model, it is quite a phenomenon of the heat exchanger being plugged up with scale deposits. If so, you will need to flush your water heater. Last but not least, check and minimize the hot water demands by turning off extra hot water fixtures.

FAQs:

In Closing!

If the hot and cold water not mixing in the shower, the highest possibility is that the mixing valve of your shower has started malfunctioning. Either it is not calibrated correctly or blocked by sediment or lime-scale build-up. If so, adjust the shower valve correctly and clean the blockages from it.

In case you have a bad mixing valve, consider replacing it with a new one. Now in case, you have apressure-balancing mixing valve, we recommend switching to a thermostatic mixing valve.

The thermostatic mixing valve will sense the temperature of the water and blend thehot and cold water more precisely. This will allow you to enjoy a consistent and comfortable shower experience! So what are you waiting for?