Is Your Water Heater Suddenly Scalding Hot? Learn Why and How to Fix It (2023)

Optimal Water Heater Temperature

You want your water heater to provide hot water that doesn’t get to the point of scalding. To prevent this, the U.S. Consumer Product Safety Commission (CPSC) recommends not setting your water heater higher than 120°F. Most installers set new water heaters to a default temperature of 120°F. While you can raise the temperature on many models to 140°F or higher, especially models designed for commercial use, most manufacturers include features to keep the unit set to a safe temperature .

Problems Caused By Excessively High Temperatures

Water heater temperatures that are too hot can result in dangerous conditions for you and also damage to your unit. These are the top problems caused by water heaters with excessively high temperatures:

  1. Burns: If you allow hot water from your water heater to touch your skin at high temperatures, you may burn yourself. The higher the temperature and the longer you keep your skin underneath the water, the more severe the burn. For example, 140°F water can burn you in only five seconds.

  2. Increased Energy Consumption: It takes substantially more energy to heat water to a higher temperature, especially if you have a tank-style unit. Whether you have propane, natural gas, or an electric water heater, you will pay more in utility bills when your water heater generates excessively hot water. When set to 140°F instead of 120°F, your water heater will waste up to $61 annually in standby heat loss and $400 in direct consumption .

  3. Faster Deterioration of Water Heater: Higher water temperatures lead to more sediment buildup and expedited corrosion in your water heater. These actions will cause the tank to deteriorate more quickly than if the unit runs at a lower temperature.

Common Causes For a Suddenly Too Hot Water Heater

Why is your water heater suddenly scalding hot? When your water heater overheats, you need to diagnose the source of the problem. Consider these common causes for suddenly "hotter-than-normal" water heater temperatures:

  1. Temperature is Set Too High: Too hot water temperatures can derive from an improper setting. This can happen at installation or if a family member made an adjustment for a hotter shower. Check the temperature of your water heater to ensure it doesn’t exceed 120°F. If it's set higher, follow the necessary steps for your hot water system to change the temperature on your heater.

  2. Damaged Pressure Relief Valve: If the pressure relief valve becomes damaged, hot steam can develop inside the water heater tank, resulting in hotter water. You can recognize a faulty pressure relief valve by checking for whistling noise, leaks at the pressure relief valve, or water pressure problems. If you suspect a damaged pressure relief valve, it's important to have it repaired or replaced by a professional.

  3. Mineral Sediment Buildup: If sediment buildup develops in your water heater tank, it can cover the heating elements, forcing them to work harder and overheat the water. You can tell if you have mineral sediment buildup when you notice a popping noise coming from your water heater. To prevent sediment buildup, consider buying a water softener .

How to Fix a Water Heater That Is Too Hot Or Overheating

The solution to scalding hot water temperatures varies based on the cause of the problem and the type of water heater in your home. Use these steps to reduce unreasonably hot water temperatures:

Gas Water Heater Too Hot: Steps to Fix

  1. Set Temperature: Find the gas valve, which will also have a dial for the temperature setting. Ensure you have the unit set to your desired temperature .

  2. Flush Water Heater: Flushing your water heater will remove the sediment buildup around the heating element. Flushing the water heater consists of draining the water heater tank and refilling it with water. Continue the process until you no longer see sediment in the water.

  3. Replace Damaged Components: Sometimes, the water temperature gets too hot due to a faulty component. The three components that may possibly cause the problem are the thermostat, heating element, or pressure relief valve. If your water heater is alternating between too hot and too cold, test the thermostat or heating element.

Electric Water Heater Too Hot: Steps to Fix

  1. Set Temperature: To set the temperature on your conventional electric water heater, find the temperature control behind the access panel. The temperature control can come in the form of a dial or a digital control panel. Check the temperature and lower it if necessary.

  2. Test Thermostat: Test the thermostats in your water heater to verify proper function. Keep in mind that most home water heaters use a dual-heating design, meaning you will need to test both thermostats.

  3. Reset Water Heater: Many issues with electric water heaters involve malfunctioning thermostats. Find the red reset button on your unit and reset it to see if that resolves the problem .

  4. Replace Faulty Thermostat: If the reset does not resolve the issue, you will need to replace the faulty thermostat. Refer to the manufacturer's instructions or consult a professional for guidance on replacing the thermostat .

Tankless Water Heater Too Hot: What to Do

  1. Set Temperature: In most cases, tankless water heaters will have a digital control panel to make setting the temperature easy. Check the digital temperature display and change it to the desired temperature if it's set too high. Some tankless water heaters even come equipped with smart features that allow you to control the temperature from an app on your smartphone .

  2. Tighten/Replace Temperature Sensors: The sensors in your tankless water heater tell the thermostat when to generate heat. If the sensors don't communicate with the thermostat properly, it can lead to high water temperatures. If adjusting the temperature doesn't solve the issue, tighten the temperature sensors. If tightening doesn't work, consider replacing the sensors.

  3. Wash Inlet Filter: Your water heater's inlet filter, located at the cold water supply, requires annual cleaning. This device protects your unit from scale, but it won't work properly when dirty. Clean the inlet filter when you flush the water heater by running it under a faucet or using a cotton swab.

Quick-Read FAQs For Too Hot Water Heater

Why is my hot water getting too hot? The main reasons your home's hot water gets too hot include improper water heater settings, sediment buildup on the heating element, and a damaged pressure relief valve.

How do you know if your hot water heater is overheating? To find out if you have an overheating water heater, check the temperature setting on the device. You can also use a thermometer at your hot water faucet. Reduce any temperature over 120°F.

What happens if a hot water heater overheats? If your hot water heater overheats, you may experience burns on the skin, low-efficiency levels, and increased deterioration of your water heater. If caused by a damaged pressure relief valve, it can even lead to an explosion. To avoid this rare but dangerous situation, make sure to look for the warning signs of suddenly hot water and other issues .

What do I do if my water is too hot? If your water heater is suddenly scalding hot, check the temperature on the thermostat, flush the unit, and replace any faulty components. Keep in mind that different unit types may have slightly different procedures.


In conclusion, it's important to maintain the optimal temperature for your water heater to prevent scalding and potential damage to the unit. By following the recommended temperature guidelines, identifying common causes for excessively hot water, and implementing the appropriate fixes, you can ensure a safe and comfortable hot water supply in your home. Remember to consult a professional if you're unsure or uncomfortable performing any of the troubleshooting steps.

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