Quick Answer
A 20 minute shower would use approximately 80-100 gallons of water, depending on the flow rate of the showerhead. Standard showerheads have a flow rate of around 2.5 gallons per minute, which would equate to 50 gallons for a 20 minute shower. However, some newer low-flow showerheads may use only 1.5 gallons per minute, using only 30 gallons for a 20 minute shower. The actual amount can vary based on water pressure, showerhead flow rate, and personal showering habits.
Calculating Shower Water Usage
The amount of water used in a shower depends on two key factors:
- Length of shower time
- Flow rate of the showerhead
To calculate shower water use, multiply the shower time by the flow rate of the showerhead.
For example:
- 20 minute shower
- Standard 2.5 gallon per minute showerhead
20 minutes x 2.5 gallons/minute = 50 gallons
So a 20 minute shower with a standard showerhead would use around 50 gallons of water.
If you had a low-flow showerhead rated at 1.5 gallons per minute, the calculation would be:
20 minutes x 1.5 gallons/minute = 30 gallons
The type of showerhead can make a significant difference in water consumption over time. Upgrading to a low-flow showerhead is one of the easiest ways to conserve water in the home.
Factors That Affect Shower Water Usage
While the basic calculation is straightforward, there are several factors that can impact the actual water usage during a shower.
Water Pressure
Higher water pressure through the showerhead can increase the flow rate and use more water. With very high pressure, showerheads may exceed their rated flow rate.
Installing a pressure-reducing valve can help limit high water pressure to standard levels.
Showerhead Rating Accuracy
The rated flow rate for a showerhead, such as 2.5 gpm or 1.5 gpm, is based on meeting regulations with optimal water pressure. At lower water pressures, the actual flow rate may be reduced.
Testing the actual flow rate of your showerhead will give a more accurate baseline than the rated flow rate.
Showering Habits
The way you shower can also impact water use:
- Taking longer showers uses more water.
- Partially turning off the water while lathering reduces usage.
- Using lower water pressures saves water.
Being mindful about water-wasting habits can help conserve.
Temperature
Hotter showers tend to use more water, as people take shorter showers when the water is cold. Setting your water heater to a moderate temperature can help save water.
Leaks
Leaky showerheads, pipes, or valves can waste significant amounts of water over time. Fixing any shower leaks promptly can help reduce unexpected water consumption.
Age of Plumbing
Older homes may have galvanized steel or iron pipes that accumulate mineral deposits over time. This can restrict water flow, potentially causing older showerheads to have a lower flow rate than when new. Replacing plumbing can help improve flow.
Standard 2.5 GPM Showerhead Water Usage
Using the standard showerhead flow rate of 2.5 gallons per minute, here are some estimates for typical shower lengths:
| Shower Time | Gallons Used |
| 5 minutes | 12.5 gallons |
| 10 minutes | 25 gallons |
| 15 minutes | 37.5 gallons |
| 20 minutes | 50 gallons |
| 25 minutes | 62.5 gallons |
| 30 minutes | 75 gallons |
A typical shower of 5-10 minutes with a standard showerhead uses about 25-50 gallons.
Low-Flow Showerhead Water Usage
Low-flow showerheads have flow rates of around 1.5-2.0 gallons per minute. Here are some estimates at 1.5 GPM:
| Shower Time | Gallons Used |
| 5 minutes | 7.5 gallons |
| 10 minutes | 15 gallons |
| 15 minutes | 22.5 gallons |
| 20 minutes | 30 gallons |
| 25 minutes | 37.5 gallons |
| 30 minutes | 45 gallons |
With a low-flow showerhead, an average shower uses 15-30 gallons, saving 20+ gallons per shower compared to a standard 2.5 GPM showerhead. Upgrading to a low-flow showerhead can conserve hundreds of gallons per week for a family.
Water Usage in Old Showers
Some older showers have showerheads with flow rates as high as 3-5 GPM. At 3 GPM, a 10 minute shower would use 30 gallons of water. A 5 GPM showerhead could use up to 50 gallons in just 10 minutes.
Replacing these older, high-flow showerheads can potentially reduce water usage by 50% or more. Installing low-flow 1.5 GPM showerheads in older showers is an excellent way to update and realize significant water savings over time.
High Efficiency Showerheads
Advanced high efficiency showerheads can have flow rates as low as 1.0 GPM while still providing a satisfying shower experience.
Here is the projected water usage with an ultra high efficiency 1.0 GPM showerhead:
| Shower Time | Gallons Used |
| 5 minutes | 5 gallons |
| 10 minutes | 10 gallons |
| 15 minutes | 15 gallons |
| 20 minutes | 20 gallons |
| 25 minutes | 25 gallons |
| 30 minutes | 30 gallons |
A 10 minute shower uses only 10 gallons, and a 20 minute shower uses 20 gallons.
While the upfront cost is higher, high efficiency showerheads provide unmatched water savings over time. In many cases, they can pay for themselves from reduced water bills.
Estimating Shower Water Usage
To estimate your own shower’s water usage:
- Time several typical showers to determine your average shower length.
- Measure the flow rate of your showerhead in gallons per minute.
- Multiply your average shower length by the measured flow rate.
This will give you a customized understanding of your current shower’s water consumption.
You can then use this baseline to estimate potential savings from switching to a low-flow or high efficiency showerhead.
Conserving Water in the Shower
Here are some tips to reduce your shower water usage:
- Take shorter showers of 5-7 minutes.
- Install a low-flow showerhead with a rate of 1.5GPM or less.
- Upgrade to a high efficiency model rated at 1.0GPM or less.
- Turn water partially off when lathering up.
- Limit the temperature to warm vs. hot.
- Promptly repair any leaks or dripping faucets.
- Consider installing an on-demand hot water recirculation pump.
- Replace very old showerheads that have a high flow rate.
Making a few adjustments to your showering routine, showerhead, and other hardware can significantly reduce your home’s water usage over time.
Shower Water Usage FAQs
How much water does a 5 minute shower use?
A 5 minute shower will use around 12.5 gallons with a standard 2.5 GPM showerhead, and 7.5 gallons with a 1.5 GPM low-flow showerhead.
How many gallons is a 10 minute shower?
A 10 minute shower uses about 25 gallons with a 2.5 GPM showerhead, or 15 gallons with a 1.5 GPM low-flow model.
Can a shower really use 20 gallons per minute?
Some older showerheads had flow rates of up to 5 GPM, so yes, they could potentially use 20 gallons in a 1 minute shower. Modern showerheads are restricted to 2.5 GPM or less.
Does water pressure affect shower water usage?
Yes, higher water pressure can push more water through the showerhead, increasing the flow rate. Pressure reducing valves help counteract this.
Should I buy a rainfall showerhead to save water?
No, most rainfall showerheads have a higher flow rate than standard showerheads. Stick to low-flow or high efficiency models for saving water.
Conclusion
A 20 minute shower can use anywhere from 20-100 gallons, depending on the age and flow rate of your showerhead. Typical modern showers use about 50 gallons with a standard 2.5 GPM showerhead, or 30 gallons with a low-flow 1.5 GPM showerhead. Upgrading to high efficiency models of 1.0 GPM or less provides maximum water savings, using 20 gallons or less for a 20 minute shower. Being mindful of your shower time, making minor adjustments, and replacing inefficient showerheads can all help curtail residential water usage over time.
