While washing dishes manually might seem like a good way to save on water and energy costs in exchange for you doing more work than using a dishwasher, you might be surprised to know that this isn’t actually the case. Washing dishes by hand does take more physical work but actually also uses more water and energy.
Running water to do dishes manually can consume 4 gallons of water in 2 minutes while an energy efficient dishwasher requires 4 gallons of water per cycle. Hand washing dishes uses up to 4% of a home’s total water usage while dishwasher usage is around 1% saving you around $111 per year.
When you wash and rinse dishes under a constantly running tap, the water usage increases dramatically as does energy costs if you use warm or hot water to do so.
How much water does a dishwasher use?
In 2013 standards were put in place requiring new dishwashers to consume no more than 5 gallons (19 L) of water per load and 3.5 gallons (13 L) for compact models. An ENERGY STAR certified full size dishwasher can use as little as 3 gallons (11 L) of water per load.
Previously dishwashers built before 1994 used as much as 10 gallons per load so you can see how the usage has gone down over time as machines became more efficient.
These days it’s easy to find dishwashers that consume 3 gallons – 4 gallons per load with many water and energy efficient options such as:
Half load feature: Alerts the dishwasher that you are only washing a half load so it can adjust washing accordingly to improve water usage.
Other wash cycles: Power Scrub. Regular Wash. Delicate Wash. Quick Wash. Sanitize. Steam Clean. China/Crystal. Many newer dishwasher models have a number of choices that you can select depending on your washing needs. They adjust water usage, water temperature etc to become more efficient in terms of both water and energy use.
Food sensor: Some higher end models have a food sensing feature that keeps an eye on the food being cleaned from the dishes and if it senses that the dishes are clean, will decrease the cleaning time saving on water and energy use.
Better water filtration: As you’ll see below, washing your dishwasher filter is an important but completely overlooked task that many (most?) homeowners don’t do. Do you? We’ll talk more about that in a moment. A clean filter better cleans dishes and ensures you don’t have to rewash them.
Better water jet design: Newer models have better designed water jets than previous models. You should ensure your water jets aren’t getting clogged and occasionally clean them too if necessary.
Better rack design: Newer dishwasher models come with 3 racks for dishes and have adjustable and more rack options than before to better wash dirty dishes.
Rinse/hold feature: If you have dirty dishes but aren’t ready to do a full load, you can use this feature to rinse off very dirty dishes but not do a complete wash until the dishwasher is full.
Wash zones: Some newer models have a designated zone(s) where you can put extra dirty dishes so the dishwasher can provide a bit of extra help to get them clean.
Filter chopper: Some dishwashers come with a chopping blade or grinder that rotates at a high speed near the filter to basically chop up bits of food to fine bits so it can exit the dishwasher when the water is drained. These self-cleaning dishwasher filters increase efficiency and may result in you not having to wash your filter as frequently if at all.
Stainless steel tub: Plastic tubs may stain and get dirtier than a stainless steel tub. Plastic tubs may therefore require more manual cleaning.
Other features: There are plenty of other design features that may not save time, energy or water but are just cool to have. Modern dishwashers often put the control panel inside the door of the dishwasher rather than having it visible on the front as they used to. Newer models tend to be quieter than before too. You may also have a model with Heated Dry option which will consume more electricity than an air dry feature.
Is handwashing better than a dishwasher?
Generally speaking, handwashing dishes requires more effort, more water and more energy (electricity) usage than using a dishwasher regularly. The average person uses running water to wash and rinse dishes manually which consumes more water than an energy efficient dishwasher which uses around 3 – 4 gallons of water per cycle.
Beginning on January 1, 1994, U.S federal standards mandated that all bathroom and kitchen faucets and aerators can use no more than 2.2 gallons of water per minute. So if you were to run your kitchen tap fully open for 2 minutes, you’d use in excess of 4 gallons of water during that time. That’s the amount used by a typical ENERGY STAR dishwasher for one complete cycle.
Even if you ran your water for half that time that’s still 2 gallons plus the water you used in the sink to actually wash the dishes. And if you wash dishes each time you use them, it’s likely you use even more water (and detergent).
If you live alone or in a small household, a compact dishwasher can be an effective option although let’s face it: The average person isn’t going to install a compact dishwasher if their home was designed for a regular sized one in their kitchen. In that regard, you might be better off just using a regular sized dishwasher, filling it to a decent level, and running it as needed, or using an energy efficient setting as we’ll discuss below.
How do dishwashers use so little water?
While dishwashers have increasingly been designed to be more water efficient, how exactly do they accomplish this? Over time, water-consuming devices inside our homes in general have become more energy efficient and consume far less water than before.
Think about toilets which now use as little as 1.1 gallons per flush compared to older designs that used as much as 7 gallons per flush. They are now designed to work as well – if not better – than the 7 gallon variety with far less water consumed.
Tankless water heaters heat water on demand rather than old school tank heaters that continually warm water whether you’re using it or not so energy usage is lower.
How do new dishwashers consume so little water compared to older models and even less water than hand washing dishes?
Dishwashers fill up with around 3 – 4 gallons of water per cycle and run the water repeatedly through the dishwasher filter and back into the dishwasher again before pumping it out and refilling with fresh water. So water is used, filtered, used again and so on until the cycle ends.
How do dishwashers use so little energy?
Filling your kitchen sink with hot water to manually do dishes requires your water heater to heat the water typically with electricity or gas. Standard tank water heaters are relatively inefficient because they constantly heat water regardless of whether you’re using it or not. So in the middle of the night when you’re in bed, your water heater is keeping your water warm so that’s it’s ready for shower or bath time at any time.
A modern dishwasher uses cold water and then heats the water with its own internal heating system that does so more efficiently than your water heater, thus reducing heating costs. Like a tankless water heater, your dishwasher heats water on demand as it’s needed rather than constantly heating it in the off chance you need to use it like a tank water heater does.
How to reduce dishwasher water usage
- Upgrade your dishwasher to a more water and energy efficient ENERGY STAR or WaterSense certified model if your current dishwasher isn’t as efficient.
- Choose a model with energy efficient modes which use less water and have different temperature options for the water which further saves on energy costs.
- Only use your dishwasher with full loads. While you don’t want to overload your dishwasher, fill it efficiently rather than using it with half loads.
- If you’re single or have a small household, choose a model with options like Half Load which lets the dishwasher know that it’s only half full with dishes to adjust how it washes.
- Scrape and rinse but don’t pre-wash your plates and cutlery before putting them in the dishwasher. It beats having to re-wash your dishes after they were in the dishwasher but weren’t cleaned properly.
- Wash your dishwasher filter and wipe the inside of your dishwasher as required. More on that below. This is especially true if you have hard water in your area and don’t use a water softener.
Dishwasher won’t clean properly
While modern dishwashers don’t require you to pre-wash dishes before putting them in the dishwasher, wiping excess food scraps into your bio waste bin and quickly rinsing dirty dishes off is a good idea.
Over time, grease and food waste gets stuck in the dishwasher filtration system and depending on the design of your dishwasher, over time it will negatively impact its ability to properly clean dishes. If you’ve never cleaned your dishwasher filter before, here are a few signs that you should do so:
- Dishes aren’t being cleaned as well as they used to.
- Cutlery and dishes come out streaked after being cleaned.
- There’s a bad smell emanating from your dishwasher.
- The inside of the dishwasher is streaked and dirty.
Remember: These are dishes and cutlery that you’re eating with. You wash your bathroom and toilet every week (right?). If you want clean dishes to eat with, you have to put a bit of effort in to help your dishwasher remain clean. You’ll reduce your water usage further because it eliminates the chance that your dishes and cutlery come out dirty from the dishwasher and need to be washed manually.
Check your dishwasher manual to see how to wash your filter and how regularly you should do so. Washing your dishwasher filter is not a huge job as the video below shows.
Summary
- Using a dishwasher can save around $111 per year in utility costs over washing dishes by hand.
- Using a dishwasher also saves time when compared to manually washing dishes.
- Dishwashers heats water to around 140 degrees for hotter cleaning of dishes than you will get with manually washing them.
- ENERGY STAR estimates that during its lifetime their average certified dishwasher costs only around $35 to run each year and will save you 3,870 gallons of water over manual dish washing.