Why Does My Shower Go Cold When I Turn Another Tap On?

Showering is one of life’s necessities and can be a bit of a chore. But it’s even more troublesome when the hot water goes cold halfway through the shower! You might think it’s because another person is already taking a shower, but that’s not usually the case. So…why does my shower go cold when I turn another tap on?

Many different things can go wrong with the physical aspects of a shower. One of the most common problems is leakage or lack of pressure. When one part of the system stops working, it sends confusing signals to all the other parts of the system, and they start to malfunction.

These reasons include a small water heater, no water hammer prevention mechanism, and a lack of a thermostatic mixing valve. All of these things are simple to incorporate into your plumbing system. Add an expansion water tank (second tank), insulate your pipes, reduce water flow to your toilets, and install low-flow shower heads as additional fixes.

In this article, we will go over some simple tips on how to fix common shower temperature issues and finally get hot water all the way through to your shower when you need it most!

Why Does My Shower Go Cold When I Turn Another Tap On?


If you’re like most people, you enjoy a nice, hot shower. Yes, some studies show the benefits of an ice-cold shower. Just ask Wim Hof. But there’s nothing worse than having your hot shower suddenly go cold just when you’re starting to relax. So why does this happen?

There are a few possible explanations.

One possibility is that someone else in your home is using water at the same time you are, which can cause the pressure to drop and the temperature to decline. It’s called a “water hammer,” and we’ll talk more about this in a minute.

If you have two showers, one problem could be that your water heater isn’t big enough to handle two showers at once. This is especially likely if you have a tankless water heater. A tankless water heater is more energy efficient than a traditional water heater. If you don’t have one, consider researching the benefits. A qualified, local plumber can install one easily if you do not have the required skill set. Also consider investing in a larger water heater. This will ensure that you always have enough hot water for multiple showers.

At my house, we installed low-flow showerheads, which will help conserve water and reduce the likelihood of someone else using water while you’re showering. Having SIX daughters, you can trust me when I say…it helped in more ways than one!

Worst-case scenario, you could try taking shorter showers, so there’s less of a demand on the hot water supply…but who wants to do that?!

No thanks!

Whatever the reason, it’s annoying to get spiked with a cold jab during a hot shower. And it can even be dangerous if you’re not careful. Whatever solution you choose, make sure you take action so that you can enjoy your next shower without any interruption!

What Is A Water Hammer

A water hammer is a condition that can occur in your plumbing system when there is a sudden change in water pressure. This can happen when a valve is turned off too quickly, or a faucet is turned on too abruptly. When this happens, it can create a loud banging noise that can be quite startling. In some cases, the water pressure can become so great that it can cause pipes to burst!

Water hammers are more than just a nuisance; they can be quite dangerous. If you have ever experienced a water hammer, you know how jarring and disconcerting it can be. This is why it’s essential to be aware of the potential for water hammers and to take steps to prevent them from happening in your home.

How To Prevent A Water Hammer

There are a few things that you can do to help prevent water hammers from occurring in your plumbing system.

  • Second, avoid turning on your faucets too abruptly. Start with a slow trickle and then increase the flow gradually. This helps prevent water hammering from sudden pressure changes.

Too late?

If a water hammer occurs, there are a few things that you can do to mitigate the damage.

  • First, turn off the valve that is causing the problem immediately. This will help to stop the flow of water and reduce the pressure in the system.
  • Next, open up all of your faucets to release any built-up pressure in the system.
  • Finally, call a plumber to come and assess the situation and make any necessary repairs.

Another way to prevent water hammer is to install a water pressure regulator. This will help to even out the water pressure in your home and make it less likely for sudden changes. You can also add a small air cushion to your piping system. This will help to absorb some of the shocks from sudden changes in water pressure. Again, consult your local professional if these things fall outside your comfort zone to address.

Understanding Water Flow And Home Plumbing

Most people take the plumbing in their homes for granted. But, when something goes wrong with the water flow or there is a clog, it quickly becomes apparent just how important this system is. To avoid problems and keep your home running smoothly, it is important to understand how your plumbing works and what you can do to maintain it.

The first thing to know is that your home’s water supply comes from either a private well or a public water system. If you have a private well, you will be responsible for maintaining it and ensuring that the water is safe to drink. If you are on a public water system, the municipality will be responsible for treatment and maintenance of the water.

Once the water enters your home, it flows through a series of pipes to different fixtures like sinks, toilets, showers, and appliances. The type of pipe used will depend on the location of the fixture and the amount of water pressure required. For example, copper or plastic pipes are typically used for indoor fixtures because they can handle low water pressure. However, outdoor fixtures like hose bibs require stronger pipes that can withstand higher water pressure without bursting.

Your home’s plumbing also has an important role in draining wastewater away from your property. Once water is used and goes down the drain, it enters a sewer line that carries it to a septic tank or a municipal sewer system. Again, the type of pipe used will depend on the amount of water flowing through it and the distance it needs to travel.

To keep your home’s plumbing system running smoothly, there are some simple maintenance tasks that you can do on a regular basis.

  • First, inspect all of your pipes regularly for leaks or cracks. Sometimes leads can be repaired with patching compound or epoxy glue. Replacement of the faulty pipes is usually the best fix.
  • Second, clean out your drains monthly to prevent clogs from forming. You can use a plunger or a plumber’s snake for this task.
  • Finally, have a professional plumber inspect your entire system at least once per year to identify any potential problems before they become serious issues.

Do I Need To Have My House Replumbed?

If you’re considering having your house replumbed, there are a few things you should take into account. The first is the cost. Replumbing an entire house can be very expensive, and it’s not something that most people can afford to do on a whim. You’ll also need to think about the disruption it will cause to your daily life. Having plumbers in your home for days or even weeks can be very disruptive, so you’ll need to be prepared for that.

There are a few reasons why you might need to have your house replumbed. One is if you’re planning to make major changes to your home, such as adding an extension. Another is if you’ve had problems with your plumbing recently, such as persistent leaks or blocked drains. If your home is more than 30 years old, it’s also a good idea to have it replumbed, as the pipes may be starting to deteriorate.

If you’re thinking of having your house replumbed, it’s important to get several quotes from different companies before making a decision. This way, you can be sure that you’re getting the best possible price for the work.

Additional Options To Keep Shower Warm

There are a few more things you can do to ensure that the temperature of your shower is maintained even if another faucet in your home is turned on.

Investing in a thermostatic mixing valve, which will allow you to better control the temperature of the water in your shower, is one choice you have. A thermostatic mixing valve blends hot and cold water in a steady stream to maintain water temperature and ensure safety while washing hands, taking showers, and/or bathing.

You also have the option of insulating your pipes, which will assist in keeping the temperature of the water consistent as it moves through the pipes.

Reduce Water Flow To Your Toilets


I used to think those movie scenes were a joke.  Where someone pulls a prank by flushing a toilet while another person is taking a shower in order to turn the hot water to cold. Turns out, that’s a real thing! Luckily, there’s an easy way to prevent this from happening: by reducing the water flow to your toilets.

Toilets are one of the biggest culprits when it comes to wasted water. In fact, toilets account for about 30% of all indoor water use. And a lot of that water is wasted because we flush more often than we need to. The average person flushes the toilet 5-6 times per day, but a single person only needs to flush 2-3 times per day.

Let’s solve two problems!

Save money and prevent cold showers by reducing the water flow to your toilets. It’s actually quite simple. Just turn the knob at the back of your toilet clockwise until it stops… then back it up counter-clockwise a half turn.  This will reduce the amount of water that flows into your toilet bowl with each flush.  Over time, it can save you a significant amount of water while helping to prevent cold showers.

It’s important to note that reducing the water flow to your toilets will not affect their performance or cause any damage. Toilets are designed to function properly with reduced water flow, so you don’t have to worry about them getting clogged or overflowing.

Adding An Expansion Tank To The Water Heater

If your home has a water heater, and most do, it’s important to have an expansion tank as well. An expansion tank is a small tank that helps to regulate the pressure in the water heater. If the pressure in the water heater gets too high, it can cause damage to the unit. The expansion tank prevents this by absorbing some of the excess pressure.

a man is installing an expansion tank

Most homes with a water heater will already have an expansion tank installed. However, if your home doesn’t have one, or if you’re not sure, it’s easy to install one yourself. Just follow these simple steps:

1. Turn off the power to the water heater. This is usually done at the breaker box.

2. Drain some of the water from the unit into a bucket. You’ll need to do this so that there’s room for the expansion tank.

3. Disconnect the cold water supply line from the inlet valve on the water heater. You may need to use a wrench to loosen the fitting.

4. Connect one end of the copper tubing to the inlet valve and run it up to where the expansion tank will be mounted on the wall.

5. Affix the expansion tank to the wall using brackets or screws and make sure it is level.

6. Connect the other end of the copper tubing to the outlet valve on the expansion tank. Again, you may need to use a wrench to tighten everything down properly.

As mentioned before, if you aren’t comfortable doing these types of plumbing repairs yourself, you can hire a local professional.


There are several reasons shy your shower may go cold when you turn another tap on. Usually, this is due to something called water hammer. What happens is that when you turn on another tap, it causes the water pressure in the pipes to change. This change in pressure causes a hammering effect in the pipes, which can cause the water to become turbulent. This turbulence can cause the water to become cold.

We covered several way to prevent this from happening. We also talked about what to do should you find yourself already having the problem. There are other issues that may be happening as well. We also discussed these and potential answers to the problem.

I hope my article has been helpful. If you having any questions or additional helpful tips, leave it in the comment section below.

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