A dishwasher is a modern convenience that many people use in the kitchen daily to save time. Washing dishes by hand is most likely the last thing you want to do in the evening after dinner. But, many people wonder if using the dishwasher uses more water than if they washed them by hand.
Dishwashers consume far less water than washing the dirty dishes by hand, in most cases. Unlike older dishwashers that used 10 gallons of water per cycle, newer designs use only 3-5 gallons per cycle. Comparatively, handwashing typically uses 27 gallons of water per session.
Knowing whether using a dishwasher is more efficient than handwashing dishes will depend on how many dishes you have at any given time.
Keep reading to learn about how much hot and cold water a dishwasher uses and what using it may be costing you over time.
How Much Hot Water Does a Dishwasher Use?
Since dishwashers are connected to the hot water line, in most cases, hot water is the only type of water used in the unit. This means that during a dishwashing cycle, the unit will use anywhere from 3-5 gallons of water.
Older dishwashers were a novel idea that was designed to save people time and money over washing dishes by hand. When first released, these units typically were known to use about 10 gallons of hot water per cycle.
As technology advanced and the need for more energy-efficient appliances came to mind, many manufacturers reworked the design to make this happen. In addition, the Department of Energy called for dishwashers to use no more than 5 gallons of water per cycle.
Manufacturers quickly worked to redesign dishwashers to be more energy-efficient, which would also conserve water as well. While many of the units that were designed met the standard regulation of 5 gallons per cycle, others went beyond this.
Some appliance manufacturers were able to create dishwashers with an Energy Star rating that used less hot water than before. Most of these modern Energy Star units use around three gallons of water per cycle.
When compared with handwashing, dishwashers use much less water. This is because while it seems that the unit is constantly using water, the fact is that they typically fill up once then recycle the water until the final rinse where they fill again
If you compare this process to handwashing which uses approximately 27 gallons of water per session, you can see that the dishwasher is much more efficient.
In most cases, when you are washing by hand, you are either leaving the water running the whole time, or you have filled an entire sink with water.
Either way, if you fill the sink to soak your dishes, it is common to drain the water after a while and then fill it up again to finish. Because of this, quite a bit of hot water is being used during the process.
At the end of the day, the hot water that is consumed during a dishwashing session is much less than you think. This is especially true if you have an Energy Star rated dishwasher that is designed to only use three gallons of water.
How Much Cold Water Does a Dishwasher Use?
The amount of cold water used in a dishwasher depends on whether the inlet is connected to the cold or hot water. The connection depends on how new your dishwasher is and how the plumber hooked your dishwasher up in your kitchen.
If you have an older dishwasher, it is most likely that your unit is connected to the hot water since this was the standard installment practice. This is also because dishwasher detergent tends to activate better in hotter water.
Many of the more modern dishwasher brands design the unit to be connected to the cold water to be more energy efficient. This is done by installing a heating element at the bottom of the dishwasher that heats the water as it enters the unit.
It is important to note that even though many manufacturers are designing them to be connected to the cold water outlet, you will need to verify that your kitchen is equipped with both cold and hot water outlets for the dishwasher.
If you have had a dishwasher previously and you are upgrading, you will need to determine if both outlets are available. If not, you may have to decide whether or not you want to incur the expense of having a cold water outlet installed.
Many less modern homes are typically equipped with only one connection to water under the sink for the dishwasher.
Additionally, dishwashers usually only have one inlet to connect water to, therefore, you will need to ensure that you have the right equipment before purchasing a new unit.
Overall, no matter if the dishwasher is connected to hot or cold water, they typically use the same amount of water. This means that the amount of cold water used in a dishwasher depends mostly on how modern the unit is.
Older dishwashing units tend to use more water, as previously stated. Compared to newer units that use about 3-5 gallons of water, older units tend to use around 10 gallons of water per cycle.
Can You Use a Dishwasher Without Hot Water?
While a dishwasher can be connected to the cold water outlet, the dishwasher itself typically has a heating unit that heats the water. This is because the unit cleans better with hot water that activates the dishwashing liquid and also sanitizes the dishes at the same time.
Many dishwasher manufacturers have created dishwashers to be more energy efficient by allowing them to be connected to the cold water outlet. While this is true and efficient, it is important to keep in mind that the unit will still heat the water which results in it running with hot water.
Because the dishwasher operates using hot water during the cycle, it is important to notice if your unit is doing this. There are times that you may notice your dishwasher running cold water during the cycle. If this is the case, you may have a problem with your unit.
When a dishwasher is running cold water during the washing cycle, it is usually an indication that your unit’s heating element may be malfunctioning. If this happens, you will need to have it replaced right away for the unit to operate properly.
It is also important to remember that, unlike the washing machine, you cannot change the dishwasher to function at a different temperature. Since this is the case, you do not have the option to run a dishwasher cold or hot.
You do, however, have the choice of purchasing a dishwasher that can be connected to either the hot or cold water outlets. It is advised that before you purchase the dishwasher that you ensure that you have the correct plumbing to accommodate the unit you choose.
What’s the Cost of Running a Dishwasher?
When it comes to running a dishwasher, the cost will depend heavily on the wattage, size, and how often the unit is in operation. With the average dishwasher being about 1800 Watts and using between 3-5 gallons of water per cycle, the cost of running a dishwasher is approximately $45 per year if you run it four days per week.
In calculating the cost of running a dishwasher there are certain factors that you should consider including the average cost of both electricity and water where you live. For example, in the United States, the average cost of electricity is $0.13 per kWh and water is $0.0015 per gallon.
As you begin to calculate the cost, you will first need to consider the average electricity cost where you live. Then, you need to know how many Watts your dishwasher is and calculate how much that is in kWh.
Since most dishwashers fall into the 1800 Watts range and most US cities cost about $0.13 per kWh, it will cost about $0.234 per hour to run your dishwasher.
Once you have the hourly cost, it is pretty easy to calculate how much it will cost you in electricity to run your dishwasher depending on how many days per week you run it. You can calculate the cost by month or year if you want to know more specific costs.
Additionally, water is calculated similarly, except it is measured in gallons or liters instead of kWh. For this calculation, you will need to also know how much on average the water is in your area.
For example, in the United States, it is estimated that water per gallon costs about $1.50 per 1,000 gallons of water. This means that one gallon of water costs $0.0015. If the average Energy Star dishwasher uses between 3-5 gallons per cycle, you can estimate that the cost per cycle is about $0.60.
Once you have this information, you can then break the cost down to how much it will cost in water per week, month, or even year. Again, this cost is going to depend on how many times per week you run your dishwasher.
After you have figured out how much both electricity and water will cost per month or year individually, you can then put the costs together to know how much it costs to run your dishwasher in total.
Doing this and then knowing how much water and energy it takes to wash dishes by hand should give you an idea of which is more energy-efficient.
Overall, considering that a dishwasher that is energy efficient only uses about 3-5 gallons of water per cycle compared to hand washing uses on average 27 gallons of water per session, it is clear that a dishwasher does not use a lot of water.
Knowing this can help you understand using a dishwasher can save you time and money.
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