Point-of-Use Reverse Osmosis Systems

A point-of-use reverse osmosis (RO) system is a water filtration device that is connected to a single fixture (e.g., under the kitchen sink) and uses the process of RO to remove contaminants from the water supplied to that fixture. RO is the process by which pressure forces water through a semi-permeable membrane, creating a stream of treated water, called “permeate,” and a stream of reject water called “concentrate” or “brine.” These systems can potentially remove water contaminants such as lead, volatile organic compounds (VOCs), PFAS, arsenic, bacteria, and viruses. Point-of-use RO systems are typically installed in residential settings but can also be found in commercial office spaces or kitchens.

Why a Specification?

While RO systems can improve water quality, these systems can also generate a significant amount of water waste to operate. For example, a typical point-of-use RO system will generate five gallons or more of reject water for every gallon of permeate produced. Some inefficient units will generate up to 10 gallons of reject water for every gallon of permeate produced. In recent years, membrane technology has improved and some point-of-use RO systems have been designed to operate more efficiently, with some manufacturers advertising a 1:1 ratio of permeate to concentrate production, meaning only one gallon of reject water is generated for each gallon of treated water. Because there is a range of water efficiencies represented within the RO system market, EPA believes these systems could be a suitable product category for WaterSense labeling. As with all WaterSense labeled products, an RO system that bears the WaterSense label would be required to meet prescribed performance standards (e.g., minimum contaminant removal rates) to ensure the product performs as well or better than typical, less efficient RO systems.

There are no current federal requirements that regulate the water efficiency of point-of-use RO systems. Due to the water-intensive nature of RO, WaterSense does not intend to promote the installation of RO systems for all applications or encourage their use over other water treatment technologies that do not waste as much water (e.g., filtration systems). However, WaterSense recognizes that RO systems might be appropriate in certain applications, depending on the user’s desired water quality, characteristics of the incoming water supply, and consumer perception and preferences. In these instances, WaterSense intends to help consumers identify and purchase more water-efficient models, thereby contributing to water and cost savings for users. WaterSense estimates that replacing a typical point-of-use RO system with a more efficient system can save approximately 3,200 gallons of water per household per year.

Read a Point-of-Use Reverse Osmosis Systems fact sheet (pdf) (549.33 KB)  for more information.

Specification Development Update

EPA is working on finalizing the WaterSense specification for point-of-use RO systems based on public comments received on the draft specification. On February 22, 2024, EPA released an update regarding specification development to inform interested parties of the current status and to solicit final comments on updated requirements related to product packaging and documentation.

• WaterSense Specification Development Update: Point-of-Use Reverse Osmosis Systems (pdf) (192.94 KB)

The public comment period for the specification development update closed on March 22, 2024. A compilation of the comments received is below.

• RO Systems Specification Development Update Public Comments (pdf) (1.06 MB)

Draft Specification

EPA released a draft specification for WaterSense labeled point-of-use RO systems on December 1, 2022.

• WaterSense Draft Specification for Point-of-Use Reverse Osmosis Systems Cover Letter (pdf) (170.98 KB)
• WaterSense Draft Specification for Point-of-Use Reverse Osmosis Systems (pdf) (261.17 KB)
• WaterSense Draft Specification for Point-of-Use Reverse Osmosis Systems Supporting Statement (pdf) (577.79 KB)

EPA is also sharing its draft product notification template for point-of-use RO systems. When EPA releases a final specification for RO systems, licensed certifying bodies will be required to submit information regarding WaterSense labeled RO systems to EPA using this template:

• Draft Reverse Osmosis Systems Product Notification Template (xlsx) (229.25 KB)

On January 12, 2023, EPA hosted a public webinar to discuss the draft specification. The public meeting presentation, summary, and recording are available below.

• RO Systems Draft Specification Public Meeting Presentation (pdf) (2.8 MB)
• RO Systems Draft Specification Public Meeting Summary (pdf) (424.27 KB)
• View webinar recording

The public comment period for the draft specification closed on February 3, 2023. A compilation of the comments received as of February 9, 2023 is below. If you have any additional comments or suggestions, you are welcome to send them to [email protected].

• RO Systems Draft Specification Public Comments (pdf) (2.01 MB)

Notice of Intent

In January 2022, EPA issued a Notice of Intent (NOI) to develop a WaterSense specification for point-of-use RO systems to reduce water waste and recognize the most efficient technologies available. In developing a potential specification, EPA’s goal is to encourage the production of and – where the installation and use of the technology is appropriate – the adoption of more efficient RO systems.

• Point-of-Use Reverse Osmosis Systems NOI (pdf) (670.04 KB)

On February 16, 2022, EPA hosted a teleconference and webinar with stakeholders to discuss the NOI. Register to view a recording of the webinar.

• RO Systems NOI Public Meeting Presentation (pdf) (2.66 MB)
• RO Systems NOI Public Meeting Summary (pdf) (269.77 KB)
• RO Systems NOI Public Comments (pdf) (2.74 MB)  - (comments received through May 24, 2022)

Are you interested in finding out more about the development of a WaterSense specification for RO systems? Please email [email protected] to be added to the stakeholder list.