Dishwasher Water Temperature: What the Standards Say

What the standards say

The number most often quoted for dishwasher water temperature comes from the ENERGY STAR program, which states that certified dishwashers boost water temperatures to 140 degrees Fahrenheit, allowing improved disinfection compared with hand washing. That figure describes what the machine can achieve during a cycle, not a minimum temperature you must supply at the inlet.

ENERGY STAR is a voluntary labeling program administered with the Department of Energy. The dishwasher criteria effective July 19, 2023 set maximum energy use in kilowatt-hours per year and maximum water use in gallons per cycle, and the energy figure includes the electricity used to operate the machine, heat the water, and dry the dishes. Because heating water is counted directly, temperature is part of how efficiency is measured.

The Department of Energy's Appliance and Equipment Standards Program issues the test procedures and regulations behind those numbers, and it works with the EPA so that products bearing the ENERGY STAR label meet the specification. For a buyer, the practical point is that an internal water heater is expected equipment on a modern dishwasher.

What temperature should the water be at the inlet?

Manufacturer installation instructions generally ask you to connect a built-in dishwasher to the hot water supply. The exact inlet recommendation varies by model, so your machine's manual is the final authority. A reasonable habit is to run the hot tap closest to the dishwasher for a minute or two before starting a load, so the supply line is already filled with hot water when the machine fills.

The dishwasher does not depend on the incoming water alone. ENERGY STAR certified models are expected to have heaters that raise the wash water to the higher temperatures needed for cleaning and disinfection. The 140 degree figure is what the machine can deliver after its heater has done its work, and not every cycle reaches that level.

Consider pairing this article with the explainer on cycles to see where temperature fits in the normal, heavy, and sanitize options.

How to check the water reaching your dishwasher

Start at the shutoff valve. Built-in dishwashers connect to the hot water line under the sink or in the cabinet beside the machine. Run the nearest hot tap until the water is fully hot, then feel the supply line near the dishwasher connection. If the line is warm, the water heater is doing its job. If it stays cold, the supply may be tied to the cold line, or the water heater setting may be too low.

For a more precise check, use an instant-read thermometer. Let the tap run, fill a cup, and take a reading. Compare that number with what your manual recommends for the incoming supply. You are looking for a consistent hot supply, not an extreme one.

Water pressure matters just as much as temperature. A dishwasher's fill valve needs enough flow to fill correctly, and a restricted or kinked supply line can make cycles run long or sensors misread. See inlet water pressure for what to check.

Sanitize cycles and the heat boost

A sanitize cycle exists to reduce bacteria on dishes, and it does that by holding the water at a higher temperature for longer than a normal wash. ENERGY STAR's 140 degree figure appears in its discussion of disinfection, and it is the benchmark most buyers will see quoted. The cycle time is longer because the dishwasher pauses to heat the water to that target.

If disinfection matters to your household, look for a dishwasher with a dedicated sanitize cycle or a high temperature wash option. Both features raise the wash water temperature and extend the cycle, and both add to the energy the machine uses. That energy is part of the annual figures on the machine's label, so the feature is a deliberate trade-off.

For the difference between a sanitize cycle and a high temperature wash, read the sanitize cycle guide and the high temperature wash guide.

Temperature, energy use and water use

Heating water is the largest energy load in a dishwasher cycle, and the ENERGY STAR criteria are written around that reality. The standard caps energy use per year and water use per cycle, with the energy figure covering the electricity used to heat water for washing and drying. A machine that heats water efficiently can earn the label while using less energy overall.

Water use is related to energy use because every gallon the machine heats costs energy. The EPA reports that the average American family uses more than 300 gallons of water per day at home, with about 70 percent of that use indoors. A dishwasher that cleans with less water also needs less energy to heat it, which is why the two limits sit side by side in the standard.

For the savings side of that equation, see dishwasher water usage per cycle and how to read the energy guide label.

Read the manual for your model

General guidance gets you only so far. Each model has its own inlet requirements and cycle behavior, and manufacturers publish installation instructions and owner manuals for that reason. Bosch, for example, points owners to installation and owner manual resources on its website. Find the manual for your exact model and look for the section on water supply before you adjust anything.

If you are shopping rather than troubleshooting, use the features list on the model's spec page to confirm that a sanitize cycle or high temperature wash is included. Then pick the size and type that fits your kitchen. See built-in dishwashers, compact built-ins, and portable options.

What to pick for your use

Questions

What temperature does a dishwasher need for a sanitize cycle?

The commonly quoted figure is 140 degrees Fahrenheit, from the ENERGY STAR program, which says certified dishwashers boost water to that temperature for improved disinfection. A sanitize cycle holds the water at that level for longer than a normal wash, which is why it takes more time.

My incoming water does not feel hot. Is that a problem?

Usually yes. A dishwasher is designed for a hot water supply, so if the line stays cold, check the shutoff valve, the supply connection, and the water heater setting. Run the nearest hot tap for a minute or two and feel the supply line again.

Can the dishwasher heat the water itself?

Yes. Modern dishwashers have internal heaters that raise the wash water above the inlet temperature, and ENERGY STAR's figures assume that heating is part of the cycle. The inlet still needs to be hot, because the heater is not sized to make up a completely cold fill.

How do I measure the temperature at the inlet?

Run the hot tap closest to the dishwasher until it is fully hot, fill a cup, and take a reading with an instant-read thermometer. Compare that reading with the recommendation in your model's installation manual.

Does a hotter cycle use more energy?

Yes. Heating water is the largest energy load in a dishwasher cycle, and a sanitize or high temperature wash extends the cycle and adds energy use. That additional energy is included in the annual figures on the machine's label.