How to Fix Fluctuating Shower Water Temperatures

Imagine coming home from a long day at work or a tough gym session and excitedly hopping into the shower for that nice, refreshing bath…only to be greeted by scalding hot or ice-cold water midway. Not only is this frustrating, to say the least, but can also be quite dangerous! 

While shower water temperature keeps changing is a common household problem, it is pertinent that you should address it diligently. After all, you don’t want to risk burning your skin after an abrupt change of temperature.

So, how can you fix fluctuating shower water temperatures? 

Well, as with all things, investigation, identification, and isolation are key. Let’s look at the common reasons why your shower temperatures keep fluctuating to see just how you can adequately address it.

woman checking the shower’s temperature


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Reasons Your Shower Water Temperature Keeps Changing

The one good thing about common household problems is the variety of solutions that are readily accessible or even on-hand. After all, you’re not the first person to go through these problems. So before chucking out your water heating system and replacing it, a simple investigation and isolation of probable cause/s can be just what you need to fix your current system. 

And, while calling for professional help may be the easiest fix, simply isolating the problem could save you on a multitude of costs if the actual issue is easily fixable through DIY. 

Your Hot Water Tap is Not Fully on

man turning the hot water shower knob

Often, most household issues stem from a simple problem. In this case, it could be as straightforward as your hot water tap not being fully on. 

Learn More: Try a digital shower control system for the perfect water temperature.

Try Turning on Your Water Heating System at the Highest Temperature

Primarily, while we think going from cold to hot temperatures is as easy as flipping a switch or pressing on a tab, instant hot water systems are actually highly susceptible to fluctuating water temperatures due to improper thermostatic regulation. 

Often, this can be because of your water pressure. It could be that your water pressure is too weak to adapt to the temperature of your preference. That’s why it might be best to turn it on at max heat and reduce it from there.

As such, a great way to find out if this is why your shower water temperature keeps changing is by turning your hot water tap at the highest heat level and then using the cold tap to regulate the temperature. 

Basically, you reduce the heat versus cranking up the heat. If you’re lucky, this could be what you need to fix the inconsistency, but if not, a further investigation might be in order. 

Common Problems with Hot Water Systems

man adjusting the main water valve

Again, as with all household problems, isolation is key! If the first fix doesn’t rectify your issue, then you may have to take a closer look at some common water heater problems to determine the right direction for proper resolution. 

Uneven Distribution of Water Pressure

plumber adjusting the pressure gauge

As with most plumbing issues, the best step is always to check your pipes. Often, when installation is done DIY or water distribution is improperly accounted for, the significance of pipe sizes is downplayed. It may mean that the diameter of your pipes is too small to distribute water pressure evenly properly. 

To give some oversight, you can view the plumbing configuration of your home as a tree. There’s the trunk (a large diameter pipe) and the branches (smaller diameter pipes). These branch pipes are offsets of the trunk pipes and are often linked to bathrooms, kitchens, and other water-reliant fixtures in your home. 

So, let’s say while you’re taking a bath, someone uses the toilet or is showering in the other bathroom. It may impact your water pressure as you shower as another branch is demanding water.

In turn, this may cause fluctuations in water temperatures. That’s where all the age-old cartoon jokes or pranks of flushing a toilet while someone is showering come from. 

To rectify this, you’ll have to increase the trunk pipe diameter or branch pipe diameter. 

Hiring a professional plumbing service can change and reconfigure the pipes for distribution. As such, we only recommend doing this for building newer homes as the overhauling itself will cost an arm and a leg at the very least. 

For those with older homes, you may want to consider switching to tankless shower heaters or install Pressure Balancing Valves.

Insufficient tank size

a picture of an old hot water tank

If the problem isn’t the pipes, it might be the actual tank size of your water heater

When isolating the issue to tank size, try estimating how much hot water your household uses. As a given rule of thumb, most showers use approximately two gallons per minute. 

So, if you weigh this with the number of showers, faucets, and other hot water fixtures in your home and the average time they are used and come up with a higher number than your tank capacity. The most likely cause for temperature fluctuations may be a lack of hot water itself. 

Once identified, you have two options to rectify this issue: 

  1. The affordable fix – Limit the use of hot water per fixture, meaning you set an appropriate amount of time for showering before all your hot water depletes. It is a great way to solve this problem without shelling out money and save money on your next water bill.
  2. The professional fix – If limiting showering time and the use of hot water in other fixtures in your home is too much to control (as may be the case for large households), investing in a higher volume capacity tank may solve the problem.

    If you opt for this route, you’ll have to account for professional installation because DIY-ing may cause severe long-term problems. 

Blocked Pipes

plumber checking shower pipes

As time passes, the natural occurrence of blockages and pipe corrosion can severely affect water pressure, drainage, and shower temperatures. 

If you have blocked shower pipes, there is an uneven water flow, resulting in inconsistent water temperatures. 

To identify and solve this issue, you may have to call your plumber to check your pipes for any blockages or corrosion. In the best-case scenario, a simple cleaning can do the trick. However, if you have older and rustier pipes, a complete replacement may be your only solution. 

Check Your Thermostats

woman adjusting the hot water system

Whenever you’re dealing with shower temperature problems, you must check your thermostat. If left unmaintained or broken, this may lead to severe risks such as burning your skin! 

Luckily, most modern water heaters come with emergency safety features that automatically turn off your tank when your water temperature reaches a certain heat intensity. 

However, in some cases, such as rotating power outages and uneven distribution of water pressures can trigger your emergency thermostat to trip. It means when you turn it on again, it will continue raising temperatures even when past the safety threshold. 

While hazardous (and a very good reason to call your plumber or repairman), broken emergency thermometers are often not the cause of why shower water temperature keeps changing. 

In fact, you can quickly solve tripping emergency thermostats through a simple reset. 

A more common issue is faulty temperature regulators. It is not reading your water temperature accurately and is significantly increasing or decreasing the heat intensity of your shower water. 

You may need to contact your plumber to repair or replace your regulator for this type of issue.

Too Many Hot Water Outlets Being Used

As mentioned in the uneven distribution of water, the usual plumbing structure is segmented into branch pipes. 

When you and your family simultaneously use too many water heating fixtures, this will almost always result in fluctuating shower water temperatures. 

To rectify this, you may have to be cautious of taking showers when other people are using hot water or opting for additional water heating tanks – if you have the space and budget, of course. 

Although, a quick remedy might be to limit the number of water fixtures in your home using hot water or opting for tankless heaters in your bathrooms. 

When you and your family simultaneously use too many water heating fixtures, this will almost always result in fluctuating shower water temperatures. 

To rectify this, you may have to be cautious of taking showers when other people are using hot water or opting for additional water heating tanks – if you have the space and budget, of course. 

Although, a quick remedy might be to limit the number of water fixtures in your home using hot water or opting for tankless heaters in your bathrooms. 

Lack of or Faulty Pressure Balancing Valve

plumber fixing a faulty pressure balancing valve

Inspect your water heater and check if a Pressure Balancing Valve is present. And, if it is, is it working properly? 

Essentially, a thermostatic mixing valve (TMV) is a valve that blends hot and cold water to guarantee that you get safe and consistent shower temperatures. 

You can learn more about the importance of TMV by watching this video: 


These open and close depending on your water flow. Like in instances wherein someone is washing the dishes or flushing the toilet, the water pressure in your shower will likely decrease. So, to offset this, the TMV will either send scalding water or freezing water to regulate the temperature of your water to keep it consistent. 

As such, a lack of or faulty TMV might severely cause fluctuations in your shower temperatures as nothing is regulating the water flow. If that’s the case, hiring professional help is necessary as replacing or repairing these can be pretty tricky.

Blocked or Faulty Shower Cartridge

As with pipes, shower cartridges are parts of your plumbing system that require maintenance from time to time. In fact, if you are experiencing these occurrences alongside fluctuating shower temperatures, then a blocked or faulty shower cartridge might be the core problem: 

  1. Shower handles are hard to turn 
  2. Leaking showerhead or faucet even after being switched off completely
  3. Decreasing water pressure over time 

A blocked shower cartridge is a result of lime and gunk buildup or the inevitable corrosion of constant use. If you have these problems mentioned above, it might be time to clean, repair, or even replace your shower cartridge

Routine Checking and Maintenance is Key

As with most household problems, you can resolve fluctuating shower water temperature by conducting a regular inspection. By building the habit of routine checking, you can quickly identify what aspects you have to maintain to avoid fluctuating shower temperatures and other water flow problems without spending a fortune on repairs and replacements. 

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