Highest allowed shower head flow rate per states and cities 2022

Updated: 3 days ago

We summarized the highest flow rate allowed shower head gpm in the United States in 2022 with the granularity to city level. Let's find out what is the highest possible flow rate you can get on showerheads in your area.

What is GPM, gallons per minute

Standard way to describe how many gallons of water does a shower head use is GPM, which stands for gallons per minute, at an 80 psi in-coming pressure. 1 GPM rating means that there is 1 gallon of water coming out of the shower head every minute when water pressure is at 80 psi. 1.8 GPM means 1.8 gallons of water and so on.

Typical household water pressure in the US is between 50 psi~ 80 psi, therefore often times the actual flow rate out of the shower head would be less than the flow rate rating because they are rated at 80 psi. So if you have a 1.8 gpm showerhead like us in California, the typical shower use would be 10 to 12 gallons. Easiest way to measure flow rate is to get a bucket, timed for 1 mins and measure the volume or weight of the water coming out. A flow meter can also be used but it often needs to be calibrated.

Nationwide mandate - 2.5 gpm

National standard of maximum 2.5 gpm flow rate for shower heads was established through the Energy Policy Act (EPAct) of 1992 in order to save water. If the state, county or city of residency does not specify a maximum flow rates for shower heads, a 2.5 gpm shower head is the maximum one can get. For shower heads made pre 1990s, it is still possible to find 3.5 gpm flow rate or even higher. So hold the thought for a 5 gpm one.

WaterSense Certification

Another certification that could be required is WaterSense. WaterSense is a voluntary program run by EPA to help conserve water across kitchen and bath. WaterSense collaborated with the American Society of Mechanical Engineers (ASME)/Canadian Standards Association (CSA) Joint Harmonization and established the first universally accepted criteria for measuring showerhead performance.

The requirements address flow rates across a range of pressures, spray force, and spray coverage, three key attributes of showerhead performance, according to consumer testing. Therefore not only that WaterSense regulates maximum flow rates, it defines minimum flow rates as well. After measuring flow rates of shower head at 80 psi to make sure it is below the rating, it then measures 45 psi and 20 psi which represents the low end and very low end of possible water pressure. The flow rate at 45 and 80 psi the tested flow rate cannot be less than 75 percent of the showerhead’s maximum rated flow rate value and at 20 psi the tested flow rate cannot be less than 60 percent of the showerhead’s maximum rated flow rate value. WaterSense flow rate is also measured at 38 degree C.

Here's a break down of shower head minimum flow rate vs. pressure should be for a WaterSense certified shower head.

Example of minimum allowed flow rates

80 psi water pressure

45 psi water pressure

20 psi water pressure





2.0 gpm

1.5 gpm

1.5 gpm

1.2 gpm

1.75 gpm

1.3 gpm

1.3 gpm

1.1 gpm

1.5 gpm

1.1 gpm

​1.1 gpm


1.0 gpm

0.8 gpm

0.8 gpm

0.8 gpm

Maximum flow rate and WaterSense requirements for different regions

Here is a complete list of highest GPM shower heads other than the 2.5 gpm national standard. Higher flow rate shower heads can not be shipped to locations where a flow rate mandate is enforced. Please note that plumbing code changes and we might not be able to keep up to date on the latest regulation, check with the local municipal officials for the up-to-date regulation.

Scottsdales, Arizona - 2.0 gpm

West Hollywood, California - 1.5 gpm

California - 1.8 gpm

Ft. Collins, Colorado - 1.8 gpm & WaterSense certified for new constructions

Colorado - 2.0 gpm & WaterSense certified

Miami-Dade County, Florida - 1.5 gpm & WaterSense certified

Broward County, Florida - 2.0 gpm & WaterSense certified

Hawaii - 1.8 gpm

Chicago, Illinois - 2.0 gpm & WaterSense certified

Massachusetts - 2.0 gpm

Rockville, Maryland - 2.0 gpm

Nevada - 2.0 gpm

New Jersey - 2.0 gpm & WaterSense certified

New Your City - 2.0 gpm & WaterSense certified

Oregon - 1.8 gpm

Vermont - 2.0 gpm

Washington - 1.8 gpm

Washinton D.C. - 2.0 gpm & WaterSense certified

More rinsing and automatic shower saving - Oasense Reva smart shower head

Although EPA estimates that switching to a WaterSense labelled showerhead could save 1,200 per shower per year, if we use a typical water saver shower head that has flow rates lower than 1.5 gpm, a.k.a a low flow shower head, it could compromise the showering experience and lead to longer shower thus off-set the water saving.

Studies have shown that 1.8 gpm is the minimum flow rate to have a good rinsing. To save water further and still have a full enjoyable rinsing experience, Oasense Reva smart showerhead with its latest embedded sensor technology is a great way to enjoy luxury rinsing and still promotes water conservation. Reva is the most tech-advanced shower head amongst all other the shower heads that save water.

Learn more on how flow rate impacts shower pressure.

Oasense Reva smart shower combines advance sensing, machine learning algorithm that controls the built-in shut off valve that will eliminate extra water wastes when shower is not actively in use and during warm up and concentrate all the water towards rinsing, making a 1.8 or 2.0 gpm showerhead effectively a 1 gpm showerhead yet still have the high pressure that every one likes, and it can be installed in just 15 seconds without a need to remodel like other motion activated shower system.

Oasense Reva is the winner of Consumer Electronic Show (CES) 2022 Innovation award, Reddot product design award 2022, Reddot innovative product 2022, Fast company world changing idea 2020 honorable mentioned.

Learn more about the award winning Oasense product design

Learn more about Oasense's user experience design

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