Consumers and building owners continue to read and hear about the deteriorating quality of their drinking water. Chemicals such as per- and polyfluoroalkyl substances (PFAS) and lead are often found in water supplies throughout the U.S. In order to provide homes, daycare facilities, schools and commercial buildings with safer water, many are using water treatment devices designed to remove unwanted chemicals from water. Finding a product that is certified to remove the chemicals of concern is important. There are a variety of certified products available in the market that improve drinking water. However, when these products are being installed, it is equally critical to be mindful of proper supply and drain connections, and the need for backflow prevention. The goal is to improve the drinking water — using improperly installed devices or those without backflow prevention could put people at risk by introducing harmful microbial and chemical contaminants into the water supply. When these products are installed, care must be taken to prevent cross-contamination and code approved supply fittings and drain connections should be used.
A common technology used to improve drinking water is point-of-use (POU) reverse osmosis (RO). RO systems include several stages of water treatment to reduce many impurities found in drinking water. These impurities include the chemicals we continue to hear about in the news, such as lead and PFAS. Although this technology does not require a complex plumbing installation, it is amazing how many installations are done incorrectly. Following local plumbing codes and the manufacturer’s instructions is essential. To help encourage proper installation, ASSE International is working with the plumbing and water treatment industries to develop a professional qualifications (PQ) standard for the installation of water treatment equipment – ASSE 22000, Professional Qualifications Standard for Water Treatment Equipment Personnel. The goal of this PQ standard is to prevent many of the common, improper installation errors that occur today.
POU RO systems typically require a ¼” or 3/8” supply connection and a ¼” drain connection. The systems are commonly supplied with push fit type fittings on the RO, along with a polyethylene tubing for the supply and drain piping. To help ensure that the push fit fittings will not leak, the working group for ASSE 1061, Performance Requirements for Push-Fit Fittings, is developing language to include these fittings into the scope of the standard. When installing the water supply to the RO, there are a variety of code approved options. However, we continue to see the use of self-piercing saddle valve connections. Proper installation should include the use of a tee, along with an isolation valve. Various companies have developed certified, code compliant supply fittings manufactured with a variety of materials to help make RO installations safe and easy to perform.
RO systems also require a drain connection. The RO membrane uses pressure to separate ions into two streams — a purified stream (permeate) used for drinking, and a contaminant stream (concentrate) that is sent to the drain. The concentrate stream includes chemicals such as lead and PFAS. When connecting the drain line from the RO system, care must be taken to prevent cross-contamination. UPC® Certified RO products include instructions on the proper use of an air gap, or air gap device, to prevent backflow events. To encourage the use of an air gap, the industry has developed RO faucets that include an air gap. The faucet is designed with a purified water supply line connection, but also includes drain line connections and a built-in air gap. Testing requirements for air gap faucets, or air gap devices, can be found in NSF/ANSI 58, Reverse Osmosis Drinking Water Treatment Systems, or IAPMO PS 65, Air Gap Units for Water Conditioning Equipment Installation. Certified products can be found on certification bodies’ public listings, listed under these standards.
See the RO faucet illustration below – it has a built-in air gap. Some others only includes a port for the purified water. When a non-air gap faucet is used, a separate air gap device is required for code compliant installation.
A third common problem with RO installations is the use of a drain saddle. Instead of using a drain line adapter listed to the UPC, some installers use a drain saddle that requires a hole to be drilled into the drain line. Although drain saddles are not allowed in plumbing codes, it is common to see these installations used in the field. See the illustration above of a drain saddle clamped to a pipe instead of a proper drain line adapter, which includes a push fit fitting for flexible poly tubing.
The final problem, although becoming rarer these days, is the use of copper tubing on the purified water (permeate) line of the RO system. Some jurisdictions prefer the use of copper pipe for drinking water applications; in Chicago, I live in one of these jurisdictions. Copper is a great material for drinking water, but should not be used for low TDS, low pH RO water because the water is very corrosive. RO water will dissolve the copper, typically producing blue/green water with elevated levels of copper, and eventually cause leaks. Per code, the supply and drain lines shall be specified by the manufacturer (and are typically supplied by the manufacturer).
As consumers demand safer drinking water, products like RO systems will continue to gain popularity. As we work to solve water purity problems, it is equally important to prevent increased backflow risks by using a proper air gap and preventing leaks, which could cause water damage and mold, by using code compliant supply and drain connections. ASSE continues to advance the industry by developing and maintaining product performance and professional qualifications standards. Expanding the scope of ASSE 1061 to include water treatment push fit fittings and developing the new ASSE 22000 PQ standard are two examples of how ASSE’s motto, “Prevention Rather Than Cure,” is more than just words.
