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Common Causes of Sudden Water Temperature Changes in the Shower

A lot of us recognize that familiar feeling of discomfort when your hot shower suddenly becomes cold as ice. Someone in the house flushed again, didn't they? Sometimes, it's the opposite, and the shower rapidly becomes scalding, causing you to nearly break a leg as you hop out of the shower as quickly as possible. However, these issues aren't a fact of life! With the right installation, you can stop those terrible shower water temperature changes.

Why Do Temperature Changes Happen?

Flushing Problem

As we mentioned above, often, these issues are caused when water is being used somewhere else in the home, whether it's to refill a flushed toilet or to launder your clothes in the washing machine.

Why does this put such a strain on your system and cause temperature issues? Most home plumbing systems in the U.S. are set up as a "trunk and branch" system. One main pipe supplies water that smaller branching pipes take to different areas of your home. The "trunk and branch" set-up is great for efficiency and minimizing pipe replacement, but it has the drawback that all of your water fixtures use the same water.

When someone flushes a toilet, they are pulling cold water away from that main pipe. However, hot water continues to flow to the shower. Suddenly, there is no cold water to mix in with your hot water and cool it down. Your shower becomes hot water directly from your water heater! All because someone else in your home required a small amount of cold water.


Installing an anti-scald shower valve can fix this issue. There are two main valves we can install, but both maintain water temperature in your shower well.

Your Tank Storage Heater is Too Small

Taking a shower is a great way to relax and gather your thoughts. Some of us are just a bit more thoughtful than others and need 20+ minutes to do so. If that's you and you're noticing that your water goes cold or lukewarm around minute eighteen, it might just be that you've used up all your hot water. Depending on your set-up, your shower can quickly go through five or six gallons a minute. With a typical 50-gallon storage-tank water heater, you can run out of hot water early.


A tankless system is a great way to overcome this. You won't run out of hot water since the water is heated at point-of-use. This means you have an unlimited supply of hot water, though these systems can only handle a certain amount of flow. Alternatively, you could install an expansion tank or a larger storage water heater, so your hot water will last longer.

So now you know just two of the common causes of shower temperature issues. Of course, you'll want to rule out things like a broken water heater, or a mistaken set water heater thermostat as well.

If shower temperature changes are a consistent issue, give Pride Plumbing of Rochester a call at (585) 271-7150 or fill out a form online and we’ll fix it for you!