Legislative Blog
J.B. Williams, J.D.
Dishwasher Efficiencies
A Blog about Environmental impact
A Bit of Background
The following backgrounds help summarize the author's views on both the general topic: Other and more specifically Environmental impact as it relates to that topic.
Brief Summary of Other
Topics here may be related to legal matters but not innately legal. For instance, discussing grocery plastic bags versus cotton cloth bags. The item itself is not legal but many city governments have placed it into legislation.
Summary of Environmental impact
The goal here is to read studies and articles on different small items that become, or have become, an environmental target. I'm doing this mostly because I bought into some of the hype many years ago, and now sadly I see that what was being pushed as better environmentally was not.
Blog Summary
I delved into dishwashers as my first appliance. So with that being said, I can honestly say, it depends. A dishwasher can be more efficient than hand washing water wise, if you use more than 4 gallons to handwash, never pre-rinse, and only use the normal cycle. Otherwise it just depends. As far as power usage, handwashing only uses what is needed to heat the water (so this is no different than using 'tap' water in the dishwasher) and any lighting that would not normally be on during the handwashing. Again here you have to consider, am I turning on one light but not another, or is this the same light that would otherwise be running. Read the full blog for more.
Dishwasher Efficiencies
Published: 2023-09-27
After reviewing testing data and rules/regulations surrounding dishwasher efficiencies, I've found the following:
- First, testing use to be based upon 264 cycles per year, or 5.1 cycles per week or 10.2 cycles over 2 weeks. It was dropped to 215 cycles per year in 2016, or 4.13 cycles per week or 8.3 cycles over 2 weeks. They are considering 184 cycles per year, or 3.5 times per week or 7 times over 2 weeks.
- Second, water usage is currently 3.5 gallons per cycle. Some entities have waivers if they use more due to other features.
- Third, manufacturers standards influence the governments standards. Every industry has standards that are set amongst the manufacturers of the product using standards boards. This information is used when the government considers what their efficiency ratings should be. However, not all manufacturing suggestions are considered. And sadly the one I read in the upcoming changes would have actually been a positive to being more efficient and conservative for water usage; but it is not going to be implemented.
- Fourth, testing is done using a normal cycle for both tap water temperature and heated water. Interestingly though it must be run at an ambient room temperature of 75 degrees F. So varying house temperatures will affect the energy ratings.
- Fifth, to test, they soil some of a 6 piece serving set along with 8 place settings. No pots/pans seem to be included in the testing. Not all items are soiled but the total amount of soilage is included. They have specific items for soiling, including Folgers Classic Decaf, nonfat dry milk, instant mashed potatoes, and ground beef.
- Sixth, I also learned that many manufacturers do not have a specific drying element, instead they super heat the water for the last rinse cycle. This allows the water to evaporate faster due to the heat, and it adds heat to the dishwasher so the items dry faster. This is partially defeated if you open the door of the dishwasher when it hits the dry cycle.
Based upon the current 215 cycles per year, water usage is 14.47 gallons a week, 752.5 gallons per year. This assumes no pre-rinsing, either in the machines or in the sink prior to loading. And this is for running the normal cycle. Based upon manufacturer comments, and common sense, if you pre-rinse in the sink or in the machine, there will be a significant increase in water usage. I've read some things in the past about filling the sink with water and placing dishes there before loading into a dishwasher. If you fill the sink once a day and use it as pre-rinse, then you add approximately 5 gallons of water usage per day or 1,825 gallons per year. (Even at 2.5 gallons that is 912.5 gallons per year.) So I'd say that a significant amount. FYI, I approximated 5 gallons as industry states that is the average sink size.
In my house, we'd use approximately 4 gallons a day washing dishes or 1,460 gallons per year. We don't use a dishwasher and don't fill the sink. I know there are days we use the 5 gallons but there are also days we do not. More do not than do days. I know when we used the dishwasher we ran it about every 3 or 4 days or about 121 times a year. For dishwasher water usage that would be about 425.83 gallons per year. Using the 2.5 gallons per day rinse, that would add 912.5 gallons of water, equating to 1,338.3 gallons per year. So slightly less at the lower amount of rinse water. However the dishwasher values would not include the water usage for cleaning pots/pans, but the hand wash values does. The difference became 121.67 per year, or 2.3 gallons per week. Obviously we are not measuring the amount of water usage each day when we hand wash, it is based upon the total volume of the sink and the amount of water that is there each time. It's an estimate and could be off. But then again so could the dishwasher numbers. In fact, since our dishwasher is close to 30 years old, it could be using more power and more water than the 2016 efficiency numbers. And so could yours, it depends on when it was purchased and whether you purchased the most efficient item when you did (and whether they had a waiver of any kind).
I used the standard 3.5 gallons per cycle but read it could be off by 3.3% in either direction.
Whirlpool has a system that saves the final rinse water for use in the next cycle. They were granted a testing waiver but must provide data on water/energy use for drain out events and clean out events. Those events have to be done due to the storage of the water. Sounds a lot like washing machines that store the water for use again later. This isn't bad but if it sits too long, it can definitely get foul. Good concept for those that use the item more often but bad idea for those that use it less often. I can extend my washer use out to about 7 days before the stored water seems to be an issue as for as odor, at least. I would imagine it would be similar to dishwasher water storage.
By the way, the Trade Association affiliated with home appliance manufacturers, 3 California power companies, GE Appliances, efficiency organizations, Samsung, and Whirlpool all 'commented' when the rules regarding testing were being made. I am sure this implies that they help to set the standard because that is generally how this works. I'm not saying it is a bad thing but it's a bit concerning that home appliance manufacturers are getting some input, but Samsung and Whirlpool are dipping in again for further input. And I'm not sure why 3 California power companies are weighing in when no other power companies are. And to be honest, I am not sure why any power companies should be weighing in on this at all. I am beyond certain that manufacturers consider both power companies and water treatment entities when they are modifying products. If their product needed a boost in power in order to do something, and that would make it more efficient, they would need to know the likelihood of their consumers being able to get that power. (Thinking more along water pressure here as a for instance.) If it were something less likely for consumers to have, then manufacturers would need to consider that for finding a way to otherwise implement the change, or scraped the idea.
Basically from what I researched, it may be more energy and water efficient to use a dishwasher but you would have to just use the dishwasher on normal cycle. But this would be for dishes only, no cooking pans/pots. So if you run your dishwasher on normal cycle no more than 4.2 times each week, and only scrap your dishes off then you are using the least possible. If you are pre-rinsing in anyway, then running the dishwasher may or may not be the most efficient use. It may be the most efficient use of your time though.
I was curious on this because I've often wandered. We don't seem to be using more water now than we did in the past, and we stopped using our dishwasher several years ago. We generally only wash dishes once a day by hand. It's rare that we pre-rinse. But it's what is working for us, and allows us to use the china that cannot go into the dishwasher any time I want. So take the above information as a guide for yourself, and determine what works best for you. In the end, the values can be relatively close over the year, And remember a newer model at the top end may be more efficient but it cost energy/water/components to make, more was spent getting it to where it is being sold and to you. All of those need to be considered before getting rid of an older item that is still running efficiently. And don't forget any variation in your home from the 'testing' home makes a difference in outcome.
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