Do dishwashers use a lot of electricity?

Dishwashers frequently conceal their true energy consumption since the machine doesn't actually use very much in the way of electricity itself. The pump and control electronics require about 1200 watts, about the same as a blow dryer. Unless the appliance has its own onboard heater, which adds quite a bit to its power demands, that's it. The reason that the dishwasher is able to get away with such a low power profile is because it piggybacks off another 1 of your household appliances for as much as half of its energy consumption – the hot water heater.

How much water does a dishwasher use?

Dishwashers need piping-hot water to do their job effectively, and that water has to come from somewhere. The gas or electricity that the water heater needs to supply the dishwasher should, by rights, count toward the dishwasher's total energy consumption. How much energy is required depends on the amount of water the appliance needs to clean the dishes, which in turn depends primarily on when the dishwasher was manufactured:

• Dishwashers dating from before 1994 can use 10 to 15 gallons of water per load.
• Older ENERGY STAR dishwashers use 4 to 6 gallons of water per load.
• New standard-sized ENERGY STAR dishwashers use less than 4 gallons for every load.

But how much energy does a dishwasher use per load?

Take the estimates above as a general guideline, not set-in-stone figures. To provide a true estimate of how much energy a dishwasher uses is tricky, since the amount of power used by your model will vary widely depending on the manufacturer's design and which cycles you choose to run.

Different settings for soil level and the type of dishes in the load will affect variables such as the water pressure and amount of water. You may also have an option for heated drying, which essentially doubles the base electrical cost to produce another round of heat. So, your mileage may vary, but by using the average consumption rates we can get an idea of how money the dishwasher adds to your monthly utility bills.

In total, how much does it cost to run a dishwasher?

A dishwasher's base electricity usage is pleasantly inexpensive. For a 1200-watt model and a load time of 1 hour, you use 1.2 kilowatt-hours (kWh), which is about 12¢ per load on a 10¢ per kWh electricity plan. If you run the appliance 5 days a week, you'll end up paying just $2.40 each month for basic electricity consumption.

Don't forget about the hot water, however. Assuming we've got an inlet temperature of 68°F and a target temperature of 120°F, the numbers work out as follows:

• For a 1994 dishwasher using 10 gallons per load, you're looking at 1.27 kWh, or 12.7¢ per hour. That more than doubles the 12¢ cost to operate the machine's electric components, bringing your price to 24.7¢ total or $4.94 per month.
  
  
• Older ENERGY STAR dishwashers using 5 gallons per load will need 0.64 kWh, or 6.4¢ an hour. Adding the 12¢ operating cost comes to 18.4¢ per load, or $3.68 per month.
  
  
• Finally, a new ENERGY STAR dishwasher that uses 3.2 gallons per load only costs 0.38 kWh or 3.8¢ per hour, which comes to 15.8¢ when you add in the 12¢ operating cost. At 20 loads per month you're looking at only $3.16 in expenses.

How to save money when using your dishwasher

You have opportunities to whittle down the amount of money you spend on energy for your dishwasher and other kitchen appliances. Try out the following tips to keep your power usage to a bare minimum:

• Build up a full load of dirty dishes before your run your dishwasher to reduce the number of cycles you run in a week.
  
  
• Don't over-fill the dishwasher either, as the water needs room to circulate for the process to work effectively.
  
  
• Open the door to your dishwasher as soon as its cycle completes and the dishes are still hot, which will accelerate the evaporation process. That allows you to avoid the heated dry setting and use much less energy.
  
  
• Clean your dishwasher regularly to prevent the spray arm and filter from clogging with soap scum, lime scale and food particles, which will reduce efficiency and may hinder effective washing cycles.
  
  
• Upgrade your dishwasher to a new energy saving model. As you saw from the examples above, modern dishwashers have improved their efficiency in leaps and bounds.
  
  
• Avoid using the dishwasher during the hottest part of a summer day. Producing extra heat inside your house will make your air conditioner work that much harder, only increasing the amount of energy you're using.
  
  
• Consider hand washing in certain circumstances. In most cases, using a dishwasher actually uses less water than washing dishes by hand, especially if you have a high-efficiency model. However, there are times when it makes sense to roll up your sleeves and do the job the old-fashioned way, such as if you have less than a full load to finish. Just try to limit the amount of time the faucet is running, and you can still come out ahead.