Why Does My Shower Get Hot When Someone Flushes The Toilet?

Why Does Flushing The Toilet Affect The Shower?

There are few pleasures in life better than a tepid, steamy shower, especially if it’s cold outside! However, the pleasant warmth of a shower can quickly turn to shock and agony if your shower heats up when the toilet is flushed.

Shower temperature controls can be temperamental, but flushing the toilet can ruin your perfect shower settings if the shower heats up when the toilet is flushed. Why does flushing the toilet affect the shower? There could be several causes for the phenomenon, which is why it’s crucial to schedule regular plumbing maintenance.

Although your mind might jump to the most expensive case scenario — a solution that would require replacing the water heater or reconfiguring the piping in the entire house — there are several possible solutions that can prevent you from being scalded by the sudden change in water temperature.

Why Does The Shower Heat Up When The Toilet Is Flushed?

If your shower gets hot whenever someone flushes the toilet, it could mean that you have an outdated plumbing system that isn’t properly regulating your shower water pressure. A common plumbing configuration is a trunk and branch system. This where a larger diameter pipe runs along the length of the home and smaller pipes branch off of it, siphoning off water to bring to rooms with individual fixtures.

If any of the branches demand more water, like when a toilet is flushed in one room, there is less water available to all the other branches. Toilets utilized untreated water, so it doesn’t take away from the water heater’s supply of water. When the toilet is flushed, it temporarily diverts water away from the shower while the toilet is refilling.

This process causes more hot water to be pulled from the water heater to maintain the current water pressure. The lack of cold water causes the shower water to be burning hot because there is less cold water mixing with the hot water, which is almost as dangerous as a leaking water heater.

A similar event can occur where your shower water becomes freezing. If you’re showering while an appliance that requires hot water, such as a washing machine or dishwasher, is simultaneously running it can take away hot water turning your shower cold.

How To Fix A Shower That Gets Hotter When A Toilet Is Flushed

There are multiple steps you can take to prevent your shower temperature from drastically changing due to another action taking place within the house.

  1. Don’t flush the toilet while the shower is being used. This bandaid is the easiest way to prevent someone from being burned while showering. Although this route doesn’t solve the problem, working out a system to halt flushing the toilet while someone is getting clean is the method that requires the least amount of effort. Keep in mind that even the most courteous cohabitants can forget to skip the flush however, so the shower still might blast unsuspecting individuals with hot water.
  2. Reduce the amount of water in the toilet tank. Limiting the amount of water in the toilet tank will ensure it returns to its original state more quickly. Placing a brick in the toilet tank will trick the refill mechanism into thinking it’s full with a smaller volume of water. The drawbacks of this solution are that your toilet might not have the same flushing power or effectiveness. This might cause your toilet to not flush.
  3. Slow down the refill rate of your toilet tank. This solution extends the time it takes to refill your toilet and make the change in shower temperature less noticeable. Although this fix doesn’t completely solve why does flushing the toilet affect the shower temperature, it will prevent individuals from being burned by a quick temperature change. By turning the shutoff valve below the toilet to the halfway position, it’ll siphon off cold water more slowly. However, this can also increase the amount of time the individual showering has to suffer with slightly warmer water.
  4. Contact a plumber. If all else fails, the best solution is to contact a professional licensed plumber to install a thermostatic mixing valve in the shower that will automatically adjust the proportions of hot and cold water to ensure a homeostatic water temperature. Scheduling service with a professional plumber can put your mind at ease while relaxing in the shower. A licensed plumber can widen the plumbing in your home as well to better bear the strain of multiple demands for water in different rooms and fixtures in the home.
  5. If a single flush burns you, call a professional.

    If you can’t figure out how to fix a shower that gets hotter when a toilet is flushed, leave it to the experts at John C. Flood! It’s crucial to schedule plumbing maintenance to keep you and your family safe from burns.

    Although all the above solutions will work temporarily, it’s important to check with a professional plumber to make sure there’s not a more serious underlying issue at hand. Contact us today!

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