In keeping with the theme of this issue, I decided to provide some history and background into the development of ASSE 1086, Performance Requirements for Reverse Osmosis Water Efficiency – Drinking Water. ASSE 1086 focuses on the environmentally friendly aspects of the water treatment technology, while also ensuring that efficiency is not compromising membrane life.
Consumers have become increasingly conscious about the quality of their water and the amount they consume. Contaminates in water, and water conservation, are ever present in conversations about plumbing systems and how we use our water. From these conversations, the demand for better water quality has resulted in the installation of residential water treatment systems. Simultaneously, concerted actions tasked with improving system designs are addressing water scarcity issues.
There are many technologies in the market that treat drinking water, and all these different technologies have varying degrees of efficiency. One popular option is reverse osmosis (RO) water treatment. RO water treatment systems provide an excellent means of reducing contaminants found in drinking water by utilizing a semipermeable membrane to remove ions, molecules, and particles.
Traditional ROs are known to be one of the least efficient treatment products in the market. This is true because of all the water that enters the system, only a small percentage is returned to the user as drinkable. In fact, for traditional ROs, three gallons of water goes to the drain as waste for every gallon produced as treated water. Being mindful of the need for more sustainable systems, RO system manufacturers have been working to improve efficiencies by reducing the amount of rinse water needed to operate the devices.
As is often the case when making changes to complicated designs, tradeoffs that affect other aspects of the design’s performance exist. As efficiencies in the system improve, there can be a reduction in the life of the membrane. Manipulations resulting in increased efficiency of RO systems can often cause membranes to foul. Fouled membranes no longer produce significant amounts of purified water. This leads to the membranes needing to be replaced much more frequently, which can lead to increased cost of operation and customer dissatisfaction.
In recent years, it became clear that there was a need to have a standard to cover water efficiency for residential RO systems. The standard would also need to include performance testing to address membrane life concerns of high efficiency RO systems. ASSE 1086 was developed to fill this need.
There are other standards relevant to the performance of reverse osmosis treatment devices. Most notable are NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems and WQA S-300: Point-of-Use Reverse Osmosis Drinking Water Systems. Having multiple standards for the same product may seem confusing at first. However, NSF/ANSI 58 and WQA S-300 focus on the testing protocols associated with the reduction of chemicals through RO technology. ASSE 1086 addresses the efficiency rating of the system and the impact of the efficiency on membrane life. In fact, ASSE 1086 requires that the device first be compliant to NSF/ANSI 58.
So how does ASSE 1086 address the efficiency aspect of the product? The standard includes test requirements for complete systems or components, including system manifolds, RO membranes, pre- and post-filtration assemblies, and supply and drain connections.
The standard focuses on three main requirements:
- As mentioned previously, the system must be compliant to NSF/ANSI 58.
- The product must meet a minimum efficiency rating when tested in accordance with NSF/ANSI 58. Note: NSF 58 is not an efficiency standard. While the testing protocol is present, there are no minimum requirements to meet with respect to efficiency. This is where ASSE 1086 comes in, requiring the RO device to be at least 40 percent efficient.
- To ensure membranes will continue functioning for long periods of time, a membrane life test was developed. The membrane life test is an accelerated 20-day test developed to simulate one-year’s use and operation of an RO membrane.
Some other performance aspects evaluated by ASSE 1086 include verification of the reliability of the system’s automatic shut-off valve, and a flow restrictor tolerance test. These two attributes can also influence a system’s efficiency, so were therefore included in the standard.
Automatic shut-off valves are used by the system to automatically turn an RO system on and off, according to the storage tank level. When the storage tank is full, the valve turns the system off; when the tank empties, it turns the system back on to refill the tank with purified water. If the RO system’s automatic shut-off valve fails to turn off or operates inconsistently, the system could experience backpressure, thereby significantly effecting the efficiency.
The flow restrictor tolerance test was created to require minimum accuracy of capillary flow restriction devices. A flow restrictor is used to control the amount of rejected water produced by forcing water through the semipermeable membrane. Controlling the flow rate of product water vs. reject water (system recovery) is essential to optimizing the efficiency of an RO system. Therefore, the accuracy of the restrictor is crucial.
ASSE 1086, complimented with other RO product standards, helps ensure that products in the market have been evaluated to established industry criteria that meets the needs of functionality and sustainability.
When consumers are purchasing a reverse osmosis treatment system, ASSE 1086 and the associated product certification is a great tool for making informed decisions — it provides peace of mind knowing that the product’s published efficiency has been verified and evaluated to rigorous performance requirements.
