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 four 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. As described in the NOI, WaterSense estimates that replacing a typical point-of-use RO system with a more efficient system can save approximately 4,000 gallons of water per household per year.
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.
EPA invites interested parties to provide written comments or materials relevant to the feasibility of WaterSense labeling point-of-use RO systems. Please send any comments or suggestions to firstname.lastname@example.org.
On February 16, 2022, EPA hosted a teleconference and webinar with stakeholders to discuss the NOI. A summary of the meeting and compiled comments received on the NOI to date are provided below. WaterSense will continue to accept written comments and data related to the NOI to label point-of-use RO systems. Please send any comments or suggestions to email@example.com. Register to view a recording of the webinar.
- RO Systems NOI Public Meeting Presentation (pdf)
- RO Systems NOI Public Meeting Summary (pdf)
- RO Systems NOI Public Comments (pdf) (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 firstname.lastname@example.org to be added to the stakeholder list.