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Does Flushing The Toilet Make The Shower Cold

Flushing Toilet

The last thing a homeowner wants to deal with is cold showers. For the most part, a cold shower is not something that many homeowners look forward to. However, there are a few homeowners out there that do enjoy a good cold shower. Does flushing the toilet make the shower cold? No, the toilet pulls cold water when flushed and makes the shower hotter.

Let’s take a look below at what occurs.


What Occurs When I Flush The Toilet

Believe it or not, most homeowners do not stop to think about their shower and toilet working in unison. In most cases, a home has one single dedicated water line for cold water and another dedicated line for hot water. Any appliance or faucet that uses cold water will use it at the same time. Let’s see what happens when flushing a toilet while someone is in the shower.


    • Shower – once someone turns on the shower they will adjust the water temperature to their liking. The shower will utilize hot and cold water simultaneously. As each valve is opened up the shower will mix the two water lines to get the temperature that you like.
    • Toilet Flush – the toilet uses cold water to refill the tank and the toilet bowl after every flush. If you flush the toilet while someone is in the shower, cold water will be taken from the shower to refill the toilet bowl and tank. This will make the shower water hotter for a few seconds as it loses the cold water.


Flushing the toilet does not make the water colder. It actually makes it colder.


How Can I Fix This Issue

Cold showers are not on most people’s lists of things to do. With that being said, you have very few options when it comes to taking a shower and having your water mixed up because someone has flushed the toilet. Let’s take a look at the best ways to avoid this issue.


    • Avoid flushing – if you notice that someone in your home is taking a shower, do not use the toilet until they are done. This allows the person in the shower to enjoy the water temperatures that they have set forth and not worry about getting burned with scalding hot water.
    • Slow down – reducing the rate of water pressure in your toilet tank. Filling the toilet slowly will reduce the amount of cold water being used in one instance. The person taking the shower will barely notice a temperature change as less cold water is being pulled to the toilet at once.
    • Lower the toilet tank water – placing an object such as a brick or jug of water in the toilet tank will displace the water and reduce the amount needed to fill the tank. By reducing the amount of cold water needed to fill the toilet tank, less cold water is taken from the cold water line while someone is showering.
    • Install a Thermostatic Mixing Valve – this pressure-balancing valve keeps the water pressure between the hot water and cold water lines even. Also, this type of valve controls water temperature and pressure separately.


Other Recommended Maintenance

Now that you have an understanding of what happens to shower water when your toilet is flushed. Let’s read up on why your toilet won’t stop running. This could be a very annoying issue. However, it does have a simple solution.

Next, when it comes to heating your shower water, it might be a good idea to understand how long it takes for your water heater to heat up. Knowing this information that is specific to your water heater model. This allows you to calculate the heating time, based on how far the water needs to travel.

Lastly, double-check your toilets fill valve. The creation of a water hammer could occur and you don’t want that. Additionally, this could be an issue for your shower as well as the valves are opened and closed. Be sure to understand how to stop a water hammer when your toilet fill valve closes.



Call on a plumber if flushing the toilet causes you bigger issues.

When Do I Call A Professional

Experiencing issues with your toilet or shower, or both can be a nuisance for any homeowner. When it comes to flushing a toilet causing cold water in your shower, that is not very likely. However, if you have any plumbing concerns you should reach out to a professionally licensed master plumber. Additionally, call on your local home inspection team for a full plumbing system inspection. Also, they can refer you to a reputable master plumber in your area.



Determining how water works in your home is important for any homeowner to understand what happens. Knowing how your appliances use water and how your other systems work is very important. In most cases, flushing a toilet does not cause a shower to become cold. It is the opposite of that. The toilet uses the cold water that is being shared with the shower, which could make the shower hotter. If you have plumbing concerns, reach out to your local home inspection team.  Call Waypoint Property Inspection to inspect your home in Tampa, St. Petersburg, Lakeland, Orlando, Palm Beach, Ft. Lauderdale, and surrounding areas.