What Is The Best Water Heater Temperature Setting?

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Gas and electric water heater temperatures are set at the factory, but can be adjusted for your own preferences with only a couple of tools. If you have already set the temperature and are saying to yourself, “I have no hot water” or not enough of it, there are a few factors that may be affecting the heat. If all else fails, the heating element may be failing, and needs to be replaced.

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How To Check Your Water Heater Temperature

Most water heaters do not have a temperature gauge with a readout. Instead, the thermostat is marked with temperatures or heating ranges. To accurately find the hot water heater temperature, you will need a cup and a cooking thermometer.

Allow the water heater to sit for a minimum of one hour without using it, and then turn on the faucet closest to the water heater. Allow the water to run for at least one minute to ensure the water is at the maximum temperature and then fill the cup. Insert your cooking thermometer, and then adjust the settings as desired.

Recommended Temperature Settings

water-heater-temperatureWater heaters are factory set at OSHA recommended levels, around 140 degrees. On the other hand, the EPA suggests turning the thermostat down to 120 to reduce power consumption, and a booster heater to reach sanitizing temperatures at select outlets.

From another point of view, lower temperatures are better for households with small children, while higher temperatures are more efficient at cleaning and sanitizing.

My Recommendation
Personally, I believe a water heater should be set to 130 degrees in almost all cases. It's low enough to prevent scalding yet hot enough to kill off harmful bacteria.

How To Turn Up Your Water Heater

You can adjust hot water heater settings to get more hot water if you are unhappy with the recommended temperature. Hot water heater settings are easy to adjust, although electric heaters will require a screwdriver and possibly a small wrench or socket.

Keep in mind that the thermostat is factory preset to a recommended temperature and changing the setting may increase the potential for serious burns.

How to Set Temperature on a Gas Water Heater

Gas water heaters have a setting knob that can be turned to adjust the temperature. Most gas control valves have a knob with various labels such as A-B-C on them. Different brands of gas water heater control valves may have different labels. In most cases, here’s what each label means:

  • Low (or Warm) = 80-90°
  • Hot (or triangle symbol) = 120°
  • A = 130°
  • B = 140°
  • C = 150°
  • Very Hot = 160°

Sometimes there is a “Vacation” setting. This does not heat water, but keeps the pilot light ignited.

How to Set Temperature on an Electric Water Heater

Turn off the circuit breaker. Remove the access panels. Locate the thermostat adjustment beneath the insulation. Using a straight screwdriver, adjust the thermostat control towards the desired temperature. Replace the insulation and panels, then restore power. Here’s a good video showing the process:

Factors That Affect Water Temperature

Some factors that may affect your hot water temperature are the distance from the water heater to the outlet, how the pipes are installed, and the condition of the heating element itself.

Small bore pipes and long distances will require longer times for the hot water to reach the opening, for example, and pipes that run beneath or outside the home may be subject to winter or summer conditions.

If you have a large house, you may want to look into installing a hot water recirculation system which can mean less time to get hot water in all outlets of the house and well as substantial cost savings over time.

If adjusting the thermostat still doesn’t give you the right temperature, it may be time to replace the water heater element. If you don’t notice a difference in water temperature after adjusting the thermostat, it’s also possible you may have a faulty thermostat that needs replacing.

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  1. Reading this made me think of a recent lecture I attended. Remember Dr. Marc Edwards of Virginia Tech who helped prove that Flint Michigan had a lead problem in their water supply? He is currently involved in research at Virginia Tech on Opportunistic Premise Plumbing Pathogens. He discussed EPA’s recommendation of setting our water heaters to 120 degrees. According to Dr. Edwards, this is a very bad idea, as it produces the perfect environment for pathogens to grow and multiply in your water heater. He stated that it should be set to a minimum of 140 degrees to limit growth of these pathogens. Of course the problem is scalding at that temperature, which is certainly a problem.

    I solved that problem when I recently installed a new water heater in my home. I added what they call a “Water Heater Tank Booster”. It allows me to keep my water heater at 140 degrees but will mix the water exiting the tank with cold water so that my hot water can be delivered to my tap at 120 degrees to prevent scalding. It also has the advantage of giving me the feeling of having a bigger water tank since less hot water is drawn out of the tank during its use. It could literally be a potential life saver.

    • Very interesting stuff. From what I’ve researched, my recommendation of setting the temp to 130 degrees may not kill Legionella bacteria as quickly as 140, but it should still do the job. Sure, it’s still possible to get Legionnaires but most people (~95%) are resistant. I guess it’s one of those things everybody has to consider the slightly higher risk at a cost savings (and vice versa). The tank booster you mentioned is a good solution to prevent scalding if setting the water heater temp higher as well as making hot water last longer. It’s interesting that this product isn’t a bit more popular.

  2. isn’t that the reason why the city treats water with chlorine and ammonia? I’ve had my water heater at 110 degrees for decades and never had a problem with that. You drink cold water anyway.

    • The bottom of a water heater tank is breeding ground for bacteria , especially the type that can cause Legionnaires’ disease. Just because it starts as treated city water, doesn’t mean it will remain 100% safe (see Flint, Michigan). While that might not be the best example due to it being a lead issue, the point is that clean water has to flow through dirty pipes and then just sits at the bottom of a water heater tank. Bacteria loves warm-hot conditions and can quickly multiple. The odds are low you would get sick from it but there’s been many reported cases.

    • I agree….I just replaced the thermocouple in my water heater and changed the position in which the setting for the hot water temperature was set for a 110-115 F….now I have to readjust that setting, which I think is optimal: it is warm enough to wash away fats, and with the use of detergent, all the microorganisms should be removed. I also add sodium hypochlorite, a table spoon in the water a wash dishes with, and let to stay for 15-30 minutes before washing. It sets off the danger of scalding, which increases with age, and with such conditions as peripheral neuropathy, common in people suffering for many diseases, among which one can count diabetes, in which sensation of hot temperatures can be lessen enough to produce large, and deep scalding burns, serious enough!

  3. If you are worried about it, turn it up to 140 for an hour or two a week, then back down to 120. That will kill off most of the bacteria. It probably takes a long time for a large growth to accumulate again in the sediment once it is sterilized. And like another commenter said, we drink the cold water anyway.

    • The cold water comes straight from the lines, and doesn’t sit in a tank for such a long time. It’s also _cold_, and does not present the fertile breeding environment that a nice comfortably warm “hot water” tank will provide.

  4. I have a new electric water heater. The water starts to turn cold with just one person taking a shower. What could be the cause of this?

    • With an old water heater, a broken dip tube is often the issue. It would be rare on a new water heater but that’s the first thing I’d check. You’d have hot water at the start, but as soon as you start using it, cold water is refilled back into the tank. Normally this cold water goes to the bottom of the tank via dip tube but if the tube is broken, the cold water would refill at the top which is where hot water is normally taken from.

      Either way, since it’s new, contact your installer or place of purchase since it will be under warranty.

    • Check make sure the 2 elements are set to same temp. Also, make sure elements working. On older installs, many times the lower element stops working, and then you only have a short supply of hot water.

  5. Thank you for provided a wise, practical, “middle ground” solution. Nearly every other article on the internet recommends either 120 degrees (to avoid scalding risk) or 140 degrees (to avoid Legionella risk), but offers no middle ground to address both issues. I do have one follow up question: What do you think of the recommendation some experts make to turn one’s hot water heater up periodically (perhaps a couple times a year) to 150 or 160 degrees to disinfect any lingering dangerous bacteria, then return to the normal temperature?

    • Appreciate the comment. At 130 degrees, any Legionellae would die within a few hours so if that’s the regular temp, there shouldn’t be a need to go any higher since as the risk is super low. In the rare chance any bacteria makes it to an outlet, only a tiny percentage of individuals even have the possibility of getting Legionairres (and they have to inhale the hot water or steam in a shower). Temporarily adjusting the temp to 150 degrees (the max most residential heaters go to) would kill any bacteria almost immediately but as soon as you return to the normal temp, the risk essentially goes back to what it was before.

      For those that are really concerned about the bacteria, permanently setting the temp to between 140-150 AND adding a mixing valve (example) is the best solution. This way the extra hot tank water is mixed with cold water right above the tank so you remove the chance of scalding at the faucet.

  6. I have a friend who replaced his own hot water heater but installed it backwards! He would only get minimal hot water after a lengthy wait! That could be your problem. Thats why the blue/red plastic color markers are are on the tank!

  7. As noted in the link in your later response, the “Water Heater Tank Booster” mentioned in the first comment is formally known as a thermostatic mixing valve. They can be installed on new or existing water heaters. Thermostatic mixing valves also mitigate against the dreaded “flush flash.”

    • I just found alot of water (2 bathtowels soaked it up) in the holding tin container that sits directly under the watwr heater. The water was 2 3/4″ up the tank. Apparently the.water got too hot on high and the relief valve went off. This has never happened with this heater. I have had it for more than a decade. Is it the relief valve or themostat or both?
      Also the floor under the container is wet and the heater has no feet. Advice?

  8. there is a lot of very interesting and well conceived information here. i live in central arkansas and we happen to have great water here; but i do keep my gas water heater at 140. i thought about 150 for a while there, but i dont want to pay the bill for the extra heat i dont need. 140 seems perfect for our needs. dont get me wrong, it can get hot even for me. but i do a lot of baking and cooking and the high temp keeps me from constant concern about bacteria and makes clean up a relative cinch. 120 isnt hot enough, 130 might be perfect, but i prefer 140.

  9. I can’t believe that I’m setting my water heater temperature too high for so many years without something needs to be fixed. Thank you for the article.

  10. Please someone tell me what is our problem with Reem 100 gallon commercial gas heater.
    Installed just over year ago in apartment complex, new one given me nothing but problems.
    1- Temperature setting is at B, but water temperature is over 160. Triggering sensor “too hot”.
    2- Bottom is corroding already, called Reem, no replacement until visual water leaks.
    3- Setting temperature at A, water temperature is below 100.
    Please help, Thank you.

    • Sounds like a thermostat issue if the calibration is off by more than +/- 10 degrees. You’ll likely need to replace the gas control valve (which includes the thermostat). The bottom of the tank is corroding? How old is the unit?

  11. I live in a 22/unit Condo Association and about a year ago, we got a new hot water heater (Rheem-Ruud Universal Commercial Gas Water Heater). Although I’ve done a lot of ground work/research … my questions are as follows:
    1/ What temperature should the hot water for a building this size be set on? (I have pics of the thermastate).
    2/ Earlier this year, I started noticing a SMELL from the Hot Water (in the bathroom) and even noticed some health issues associated.
    3/ Thru my research I’ve discovered that it is Hydrogen Sulfide. How should this be addressed?

    • Commercial applications are a bit different that residential. You would need check state regulations. Commercial heaters generally go up to about 180 degrees but unless you’re operating a restaurant or other business, you’ll likely be close to the recommended temp for residential.

      The culprit of the smell you’re experiencing is likely the anode rod but in some cases it may be incorrect venting in the sewer lines. See: https://www.waterheaterhub.com/hot-water-smells-like-rotten-eggs-fix/

    • Great question. The A-B-C knob on a residential gas water heater usually equals 130-140-150 degrees if properly calibrated. 120 degrees is sometimes labeled “Hot” or with a little triangle icon. Use the labels as a starting point but measure the actual temperature at the closest hot water faucet if you want to be most precise.


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