How much water does a laundry load use?
A full-size washer that has earned the ENERGY STAR certification, the federal efficiency program run by the U.S. Environmental Protection Agency, uses about 14 gallons of water per load. A standard machine uses about 20 gallons per load, according to the program’s clothes washer page.
Older machines used much more. Home Water Works notes that vertical-axis washers historically used 45 gallons per load, that newer models use less than 40, and that most high-efficiency washers use 15 to 30 gallons to wash the same amount of clothes that older machines handled with 29 to 45 gallons. These figures come from different eras and reference machines than the ENERGY STAR comparison, so use them to see the trend, not to compare two specific models.
The practical point is simple: the machine you own sets most of the water per load. Your habits decide how many loads you run.
Front-load vs top-load: how much difference?
ENERGY STAR states that certified front-load washers use about 50% less energy and water than a top-load agitator washer. Compared with a top-load impeller washer, front-loaders are still about 25% more efficient in water and energy.
These are program-level comparisons, not guarantees for one machine. A specific top-loader can be more efficient than an average front-loader, and a certified model of either type is still judged by its own rating. For that reason, the calculation below uses each machine’s own water factor rather than a type average.
What does the integrated water factor measure?
The ENERGY STAR program measures residential washers with the Integrated Water Factor, or IWF. It is the water performance metric for certified residential clothes washers, and it lets you compare water consumption independently of capacity. Put simply, the IWF is the number of gallons used for each cubic foot of drum capacity. Lower is better.
Because the IWF is expressed per cubic foot, you can turn it back into gallons per load:
Gallons per load = IWF × capacity (in cubic feet)
The current ENERGY STAR criteria, last changed on April 22, 2021, set ceilings on the IWF for certified models:
- Front-loading, over 2.5 cu ft: IWF of 3.2 or lower
- Top-loading, over 2.5 cu ft: IWF of 4.3 or lower
- Compact, 2.5 cu ft or less: IWF of 4.2 or lower
These are maximums. A certified model may sit well below its ceiling, so the ceiling is a worst case for a qualifying machine, not the figure your machine uses. A 4.5 cu ft front-loader at the 3.2 limit comes to 14.4 gallons per load, close to the 14 gallons quoted for certified full-size machines.
How do I calculate my weekly and yearly laundry water?
You need three numbers: the IWF, the drum capacity in cubic feet, and how many loads you run each week.
- Find the capacity in cubic feet in your manual or the manufacturer’s specifications.
- Find the IWF in the manufacturer’s documentation or the ENERGY STAR product listing for your model.
- Multiply the IWF by the capacity to get gallons per load.
- Multiply gallons per load by the number of loads per week to get weekly gallons.
- Multiply the weekly figure by 52 to get yearly gallons.
If you prefer liters, multiply gallons by 3.785. Keep the same units throughout, and round only at the end.
Worked example: a family of four
Suppose a family of four runs five loads a week in a 4.5 cu ft machine. Here is the calculation for three cases, using the criteria ceilings as the IWF values.
Front-loader, IWF 3.2
- 3.2 × 4.5 = 14.4 gallons per load
- 14.4 × 5 = 72 gallons per week
- 72 × 52 = 3,744 gallons per year
Top-loader, IWF 4.3
- 4.3 × 4.5 = 19.35 gallons per load
- 19.35 × 5 = 96.75 gallons per week (about 97)
- 96.75 × 52 = 5,031 gallons per year
Standard machine at the 20-gallon reference
- 20 × 5 = 100 gallons per week
- 100 × 52 = 5,200 gallons per year
The gap between the ceiling-value front-loader and the top-loader is about 1,287 gallons per year for this family. If your own machine is rated lower than the ceiling, your total will be lower too. Replace the IWF values with the figures for your model, and the same five steps give your own answer.
Does load size change the water used?
The figures above are per load, so your yearly total depends on how many cycles you run. Combining small loads into one full load means fewer cycles and fewer gallons overall, provided the load still washes properly.
Many machines adjust the water level to the load, and some let you choose a level manually. Whether your machine does this, and how to choose the right setting, is described in the manual. Do not stuff the drum beyond the capacity the manufacturer lists. An overloaded drum can wash poorly and lead to rewashes, which cancel the savings.
Compact washers fall under their own ceiling, so use the 4.2 IWF value from the criteria if you own one.
How do I find my washer’s exact water use?
Start with the ENERGY STAR product finder. Listings for certified models report the water factor and energy figures for each model. Home Water Works points out that a machine’s water factor is not always easy to find, because manufacturers are not required to display it on the machine itself. If the listing does not show it, use the manufacturer’s documentation.
You can also measure the actual use of your machine. Before starting a full cycle, take a reading from your home water meter, and make sure no other tap or appliance is running. After the cycle ends and the machine has drained, read the meter again. The difference is the water used for that cycle. Repeat it with a typical load to get a figure you can trust for your own home.
The measured value includes any extra rinse or fill cycles your machine runs, which is why it can differ from the rated figure. Use it as your working number for planning, and keep the manufacturer’s rating as the reference for the machine itself.
Frequently asked questions
Why does my washer’s manual show a different number from the one I calculated?
Ratings are based on the manufacturer’s test conditions, and the criteria give ceilings rather than fixed values. Your model’s own documentation is the reference for that machine. If the difference is large, check the capacity figure you used, since it is the most common source of error.
Can a washer’s water use point to a leak?
Yes. A leak wastes water and can damage floors and cabinets. Check the fill hoses and the drain hose for drips, and look under the machine after a cycle. If water is pooling, turn off the supply valves and have a qualified technician repair the machine before using it again.
Does the energy rating matter when I’m only looking at water?
Yes, they are separate measures. The ENERGY STAR criteria set a minimum IMEF alongside the IWF ceiling, and IMEF tracks energy use rather than water. A machine can meet the water limit and still use more energy than you want, so check both figures in the listing.
