Amanda Plumbing Sewer & Drain |4425 Columbus PikeDelawareOH43015 | (740) 369-5161
Amanda Plumbing Sewer & Drain
4425 Columbus Pike
DelawareOH 43015
 (740) 369-5161

Why Does Flushing A Toilet Effect The Shower?

Why Does Flushing A Toilet Effect The Shower?

Singing in the shower may be a delightful experience, but when that soulful melody turns to a quick yelp and a few dance steps it quickly loses its appeal. A sudden onset of hot or cold water in the shower is a sure sign that someone else in the home has disregarded your comfort. The most common culprit is a flush of the toilet, but there are other activities that can leave you in hot or cold water as well. Find out what is causing temperature fluctuations in your shower and learn what you can do to solve the issue.

A Sudden Blast of Hot Water

The most common reason for a blast of hot water while taking a shower is a flushed toilet. Because the toilet uses cold water to refill the tank, the cold water from your shower will be diverted to the toilet, leaving only hot water in the shower until the toilet refills. This can produce a blast of water hot enough to burn you or to make you uncomfortable for a few moments. This typically happens in homes with trunk and branch plumbing. Trunk and branch plumbing uses a larger diameter pipe to carry the water the length of the home and smaller pipes to carry water to individual rooms or outlets, like the shower and toilet in your bathroom. Running the cold water from a faucet can have the same effect as flushing the toilet.

A Sudden Shock of Cold Water

Water in your shower suddenly turning cold can occur for a variety of reasons. If you have a small hot water tank, you could have used all the available hot water. If this is the case the water will turn cold and stay that way. If, however, you experience a sudden shock of cold water that only lasts for a few moments, it is likely that someone in your home is using the hot water. This can occur when an appliance, such as the washer or dishwasher, is running, or when someone is running hot water from a faucet. It occurs for the same reason you get a blast of hot water when the toilet is flushed. The available hot water is diverted to another source and leaves the shower with an abundance of cold water and no hot water to mix with it.


Solving the problem of getting blasted with hot water or getting drenched with cold water while in the shower doesn't need to be difficult.

  • The quickest and easiest solution is being conscious of other family members and avoiding flushing the toilet, holding off on operating appliances that use water and refraining from running faucets while someone is in the shower.
  • If this is not possible, installing a thermostatic mixing valve in the shower will likely solve your problem. Thermostatic mixing valves are designed to keep the water pressure and temperature constant. That means if someone flushes the toilet or runs water while you are in the shower the valve will detect the decrease in water pressure and automatically adjust the hot and cold water to prevent fluctuations in temperature.
  • Increasing the available water by increasing the size of the trunk and branch pipes will also reduce the problem, but may not eliminate it completely.

If you are having issues with blasts of hot or cold water in your shower, Amanda Plumbing can help you. Our trained and skilled plumbers can assess the situation and provide you with a solution that works for you. Contact us today and banish your issues with uneven water temperatures in your shower.