Do Dishwashers Save Water?

You wouldn't think it, but using a dishwasher as opposed to washing dishes by hand actually saves water and energy in the long run.

What uses less water dishwasher or by hand?

The most efficient modern dishwashers use between 4 and 6 gallons of water per cycle according to Energy Star¹. In contrast, the average faucet can run as much as 2.5 gallons per minute², according to federal plumbing standards.

Does it save water to use the dishwasher?

Assuming 2.5 gallons of water flow from your sink per minute, in 5 minutes of hand dish washing time with the hot water running, you will have used 12.5 gallons of water. That's twice the amount of water used by a modern dishwasher. From an energy perspective, it takes about 6.63 kWh to heat a 40 gallon tank of water using your electric water heater³, so you are actually using more water to wash dishes by hand than you would if you were using the dishwasher. Add to this the need for the water to be hot - using energy from your hot water heater - and you've got quite a bit of waste on your hands.

Using Your Dishwasher for Maximum Efficiency

First, make sure you have an efficient dishwasher.

If your dishwasher is old or out of date, then chances are it's using up too much water and energy. How old is too old? According to Energy Star, any dishwasher made before 1994 is a culprit. Upgrade your appliance if you fall in this category, you could save hundreds of gallons a year. Make sure that the machine is Energy Star certified. This ensures that the dishwasher is an energy efficient one.

Next, reduce the amount of time you spend hand washing dishes. Use the dishwasher whenever possible, and wait to run it until it's full.

Finally, be conscious of how you use your dishwasher. Many dishwashers also have an Eco-Mode setting⁴, which will limit the temperature and quantity water used for washing dishes. (This setting is best for lightly soiled dishes.) Other units may offer condensation drying systems, which are far more energy efficient than units that use a heating element to dry dishes.

Does running your dishwasher every day save water?

If you own a half-size dishwasher or are a big family who can fill a dishwasher in a day, then yes, running your dishwasher will save water. If we return to the figures we covered earlier, then we know that just 60 seconds of running the tap could lead to 2.5 gallons down the drain. If that’s the case and it takes you a while to clean your dishes, even as a single person, running your dishwasher daily will help.

However, if you are someone who has few dishes to clean each day and you have a dishwasher, consider washing them every other day or every third day. Just make sure you clean your plate well at dinner time or into the trash can after so you don’t get any mold.

Is it OK to use the dishwasher every day?

Yes, provided yours is a relatively new model. Anything that was manufactured in 1994 or above should be fine, but if you have a dishwasher you bought within the last few years, then yes, you can run it every day without concern. When you consider how much water you use when handwashing (2.5 gallons a minute) compared to how much a dishwasher uses throughout an entire cycle (around 6 gallons), it’s easy to see why you should use your dishwasher instead!

Should I run my dishwasher every night?

You can, again, it depends on how full the dishwasher is. If you take two days to fill it, run it every other night. Alternatively, some dishwashers have a rapid or ½ load mode for when the dishwasher isn’t full, so consider doing that if you love the ease of waking up to clean dishes. In terms of water use, it won’t matter at what time of day you run your dishwasher. You may be able to save some money on your energy bills if you only run your dishwasher when you’re about to head to bed at night since it will be at an off-peak time, but there isn’t any other reason to do so besides being able to put away your clean dishes in the morning.

Should you rinse your dishes before putting them in the dishwasher?

Nope! It’s actually more wasteful to do so because you’ll use all the water you save by using your dishwasher! Instead, make sure you clear them of bulky food before you load them into the dishwasher. Your dishwasher can do the rest. If your dishwasher has stopped cleaning your dishes properly when you run it, it likely has a problem that needs addressed. Most dishwashers don’t warrant a pre-rinse, so if it’s just missing a little bit of food, consider paying a little more for your dishwasher tablets. Often, switching brands will help.

If you’re already using a good-quality tablet, then take a look at the drain to check it’s running properly. If there’s any water sitting in the drain at the bottom of the dishwasher, then it may have a blockage which is causing the problem. Running the dishwasher empty after pouring a cup of vinegar and/or lemon juice in the drain can help shift minor blockages. If that doesn’t work, it may be time to call in an expert to diagnose and fix the problem for you or upgrade to a new model if this one isn’t worth repairing.

The best way to wash dishes to save water is to use your dishwasher.

We often associate the things that make our lives easier as being more harmful to the planet, but a dishwasher certainly isn’t one of them! Simply load used dishes into your dishwasher and run it when it’s full. If you can’t stand the idea of leaving dirty dishes out, even if they’re in the dishwasher, then feel free to run it on an eco-mode or half-full mode on a daily basis. You’ll be saving water, and you’ll likely be saving energy, too, since your dishwasher can heat up the water much more energy-efficiently than your hot water heater.

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Sources:

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1. energystar.gov/products/appliances/dishwashers↩
2. conserveh2o.org/faucet-water-use↩
3. smartenergy.illinois.edu/pdf/newsletter6_6.pdf↩
4. theguardian.com/lifeandstyle/2014/apr/25/eco-appliances-energy-saving-hints-for-dishwashers↩