Whether researching or shopping for a new shower head, you’ll find on the spec sheet the company will often list the GPM, whether in the product description or on the packaging.
Here’s why it matters:
What is GPM in a shower head?
GPM is an abbreviation for gallons per minute. This is the maximum amount of water that flows out of the shower head each minute. Companies use restrictor valves placed inside the shower head to regulate the water flow.
Why is this important?
The flow rate directly impacts the amount of water you and your family use every month.
A shower head with a higher GPM often produces a more vigorous bathing experience. However, due to the increase in GPM, your monthly water bill will likely increase.
How are flow rates regulated?
In 1992, the Energy Policy Act was signed into law. This act mandated that all shower heads sold in the United States must have a flow rate of no more than 2.5 GPM.
EPA has also introduced a voluntary program called WaterSense. This program encourages manufacturers to produce shower heads with a maximum flow rate of 2.0 GPM or less to conserve water further. Shower heads that comply will have a WaterSense label on their packaging.
State and local regulations may place additional restrictions on GPM. For example, California, Washington, Oregon, and Hawaii limit their residents to a maximum flow rate of 1.8 GPM. Furthermore, New York, Massachusetts, Colorado, Maine, Vermont, and Rhode Island have all passed laws that require shower heads to not exceed 2.0 GPM.
How does this impact the types of shower heads available?
To sell their shower heads in a particular country, state, or city, companies must meet the flow rate requirements. This means that shower heads with a higher flow rate are not available in these areas or are illegal to sell.
The absolute maximum flow rate you can purchase in the United States is 2.5 GPM due to federal regulations.
How does a flow rate impact the showering experience?
Shower heads with higher GPM rates, typically 2.0 to 2.5 GPM, often provide greater water pressure, resulting in a more vigorous showering experience. Conversely, showerheads with lower GPM rates, less than 2.0 GPM, help save water and lower monthly water bills.
The kind of experience you want will depend on your personal preferences as well as the rates that are available in your state.
Figuring out how much your shower head is costing you
How many total gallons of water your shower uses depends on two variables: the GPM of the shower head and the length of the shower. However, other considerations, such as the frequency of showering and the number of family members that share the same shower head, also must be taken into account.
As a rough estimate, here is a table outlining the average number of gallons of water used for an eight-minute shower (this was found by the EPA to be the average amount of time that a person spends in the shower):
| GPM | Number of People | Daily Usage: (GPM * 8 min) * Num of People | Annual Usage: Daily Usage * 365 days |
|---|---|---|---|
| 1.5 | 1 | 12 | 4,380 |
| 1.5 | 2 | 24 | 8,760 |
| 1.5 | 4 | 48 | 17,520 |
| 1.8 | 1 | 14.4 | 5,256 |
| 1.8 | 2 | 28.8 | 10,512 |
| 1.8 | 4 | 57.6 | 21,024 |
| 2.0 | 1 | 16 | 5,840 |
| 2.0 | 2 | 32 | 11,680 |
| 2.0 | 4 | 64 | 23,360 |
| 2.5 | 1 | 20 | 7,300 |
| 2.5 | 2 | 40 | 14,600 |
| 2.5 | 4 | 80 | 29,200 |
What about savings?
By comparing your water bill month-over-month, you’ll be able to see whether or not there are savings. However, it’s worth mentioning that installing a shower head with a reduced flow rate only impacts one of the many faucets. Usage in your sinks, dishwasher, washer, sprinklers, etc., all contribute to your monthly water bill. Most homeowners or renters will see savings of approximately $5 to $20 per month.
Low vs. high flow shower heads
Shower heads labeled low-flow often have a GPM of less than 1.8. However, the term low-flow isn’t regulated, and, therefore, the flow rate should be verified when purchasing. Conversely, shower heads with a GPM of 2.5 may be marketed as high-flow. Many larger shower heads, like rainfall or dual shower heads, often have a 2.5 GPM as the diameter of the shower head is larger.
Worth noting is that high-pressure shower heads don’t always mean that it has a higher flow rate. To provide more water pressure, these shower heads have a smaller diameter and fewer nozzles. We discuss the advantages and disadvantages of high and low flow shower heads here.
