Using a dishwasher is often seen as more environmentally friendly than hand washing dishes. After all, running a full load in the dishwasher uses less water than letting the tap run while scrubbing dishes by hand. But is that really the case? When examining the question “Does using a dishwasher actually save water?”, there are a few factors to consider.
Water Usage Comparisons Between Handwashing and Dishwashers
When comparing the water usage of handwashing dishes versus using a dishwasher, most studies find that dishwashers are more water efficient. Here’s a look at some of the research:
- A study by researchers at the University of Bonn in Germany found that handwashing used 27 gallons (103 liters) of water to clean 12 place settings of dishes. In contrast, a dishwasher used only 10 gallons (38 liters) of water for the same number of place settings.
- An older study by the University of Arizona found similar results. Handwashing used about 20 gallons (76 liters) of water compared to 10 gallons (38 liters) for a dishwasher.
- Scientists at the University of Michigan reported that a dishwasher uses about half as much water as handwashing. They estimated handwashing used about 20 gallons (76 liters) compared to 9.5 gallons (36 liters) for a dishwasher.
- Consumer Reports testeddishwashers and found they used between 3.2 and 5.8 gallons (12 to 22 liters) of water for a full load. For comparison, they estimated handwashing used about 20 gallons (76 liters).
So most research shows a typical dishwasher uses about half as much water as handwashing dishes. But the exact savings depends on your habits when washing by hand.
Key Factors That Impact Water Usage
While dishwashers generally use less water than handwashing, there are some variables that affect the precise water savings.
Your Handwashing Habits
How much water you use when handwashing dishes depends on your specific habits:
- How long you leave the tap running: It’s easy to lose track of time and leave water running the whole time you wash. Turning it on and off as needed saves water.
- How many sinks or basins you use: Washing in one or two basins uses less water than letting multiple taps flow.
- How often you replace the wash water: Changing the wash water between loads saves water rather than letting dirty water sit.
With careful handwashing habits, you could get your water use closer to what a dishwasher requires. But it takes concentration.
Dishwasher Type and Settings
The amount of water a dishwasher uses is impacted by:
- Age of the appliance: Newer dishwashers tend to be more water and energy efficient. Replacing an older model can provide savings.
- Cycle settings: Shorter, lighter cycles use less water than heavy-duty options. Choosing the right settings for each load saves water.
- Special features: Options like soil sensors adjust water use based on how dirty the dishes are, which optimizes efficiency.
Number of Loads
Handwashing may use less total water if you’re only doing occasional small loads. Dishwashers work best for full loads in terms of water savings. But over time, a dishwasher is likely to use less water than handwashing everything.
Water Heating
Dishwashers use hot water for cleaning while handwashing relies on your hands and sink water heating up. Heating water takes additional energy, so that’s a factor when comparing the overall impact.
Benefits Beyond Water Savings
Using a dishwasher offers additional advantages besides lower water use:
- Better sanitization: Dishwashers reach much hotter temperatures than handwashing, ensuring dishes are sanitized. This kills more bacteria and germs.
- Cleaner dishes: Dishwashers have high-pressure spray jets that remove stuck-on food that is hard to scrub off by hand.
- Time savings: You avoid spending time standing at the sink soaking and scrubbing dishes by hand.
- Less physical strain: A dishwasher reduces the need to stand for long periods and the hand and wrist strain of constant scrubbing.
So dishwashers provide extra benefits on top of the potential for water savings compared to handwashing.
Tips to Maximize Dishwasher Water Efficiency
You can maximize the water efficiency of your dishwasher with a few best practices:
- Only run full loads instead of doing multiple small loads.
- Avoid pre-rinsing or handwashing dishes before loading unless food is heavily caked-on. The dishwasher will clean them.
- Choose shorter cycles for lightly soiled dishes. Run heavy-duty cycles only as needed for very dirty dishes.
- Scrape food debris off dishes and remove large particles before loading. The dishwasher filters take care of small food particles.
- Let dishes air dry instead of using heated drying cycles. Natural evaporation doesn’t use extra water.
- Use your dishwasher’s soil sensor option if available. It adjusts the cycle for how dirty the current load is.
- Consider replacing an older dishwasher with a new ENERGY STAR® model to get the latest water savings features.
Smart Use Practices For Handwashing
If you do opt to wash some dishes by hand, you can use less water by:
- Only filling the wash basin or sink halfway with water instead of all the way.
- Turning off the tap while scrubbing dishes. Only use running water for rinsing.
- Using just one or two sinks for washing rather than letting multiple taps flow.
- Draining and replacing wash water between loads instead of letting dirty water linger.
- Using a sprayer nozzle on your sink if possible rather than a constantly flowing faucet.
- Scrape dishes well to remove large food pieces instead of letting water try to rinse them away.
Practicing water-efficient handwashing makes this method a lot more competitive with dishwashers for water use.
Finding the Right Balance Between Hand and Machine Washing
For most households, the best approach is probably a combination of handwashing and using the dishwasher:
- Use the dishwasher for full loads of dishware like plates, bowls, cups, pots and pans. Let it work most efficiently.
- Handwash delicate items, specialty glasses, and expensive cutlery that aren’t dishwasher safe or you prefer to baby.
- Handwash cutting boards, prep bowls, and dishware as needed right after cooking so fresh food doesn’t dry on.
- Use the sink for quick jobs like rinsing a glass or giving dishes a pre-rinse.
Finding the right balance allows you to optimize the benefits of both methods.
The Environmental Impact of Dishwashing
When considering the broader environmental impact beyond just water use, dishwashers tend to come out ahead:
- They use less water overall as we’ve discussed.
- Energy used for water heating is lower thanks to less water usage and better insulation.
- Detergents have become more concentrated and eco-friendly.
- Drying uses heat that would be wasted rather than additional energy.
However, handwashing has some advantages too:
- No electrical energy is required.
- No use and disposal of chemical detergents.
- Less manufacturing impact since no appliance is needed.
So while dishwashers win on water savings, reasonable use of both methods can limit environmental downsides.
The Bottom Line
When used properly, dishwashers generally use significantly less water than handwashing an equivalent number of dishes. However, your specific practices when washing dishes by hand have a big impact on the exact water usage and savings.
Carefully washing dishes in full sink basins, turning off the tap when not rinsing, and reusing wash water can get handwashing closer to dishwasher water usage. But it requires diligence most people don’t maintain when handwashing dishes over time.
For effortless water savings, a dishwasher is typically the better choice, especially a newer ENERGY STAR® model used wisely. But handwashing some items and loads is fine too. Finding the right balance for your home gives you the water and energy savings of a dishwasher plus the flexibility of handwashing as needed.
Frequently Asked Questions
Below are some common questions about how dishwashers and handwashing compare when it comes to saving water:
Is it really true that dishwashers use less water than handwashing dishes?
Yes, research has consistently found that dishwashers are more water efficient overall. When looking at total water use for washing an equivalent number of dishes, dishwashers use about half as much water as handwashing.
What explains the water savings of dishwashers?
Dishwashers use a variety of special design features to minimize water use. These include sensors to adjust the cycle based on soil levels, high-pressure spray jets, alternate wash and rinse cycles, and recirculation of wash water.
Under what circumstances might handwashing use less water than a dishwasher?
Handwashing very small loads could potentially use less total water, especially if you’re very careful about not letting the tap run. But for everyday loads, a dishwasher almost always wins on low water usage.
Is it better to pre-rinse dishes before loading the dishwasher?
No, skipping the pre-rinse saves water and energy. Dishwashers are designed to clean even dishes with heavy food soil, so a pre-rinse is unnecessary in most cases.
Does letting dishes air dry waste water compared to using the heated dry cycle?
No, air drying is actually the most water efficient option. The heated dry cycle uses extra water and energy, so it’s better to just let dishes air dry when possible.
Can I really trust that dishwashers get my dishes as clean as handwashing?
Yes, modern dishwashers effectively clean dishes and sanitize them by reaching much hotter temperatures than handwashing. Adjusting the cycle settings and using rinse aids ensures great results.
Conclusion
While handwashing dishes uses a minimal amount of resources, the vast majority of research shows that dishwashers are an even more water-efficient choice. As long as you use a dishwasher properly, choosing the right cycles, letting it fully load, and skipping pre-rinsing, it will use about half the water of even careful handwashing. Handwashing definitely still has its place for certain dishes and convenience. But if saving water is a priority in your home, the evidence clearly suggests letting the dishwasher tackle most loads.