At Moen, your family’s water quality and experiences with water are important to us. That’s why we’re giving you tools and resources to help you better understand and improve the quality of drinking water in your home. There are lots of strategies and solutions that you can use to filter your water, and chances are, you may already have a filter you use in your home, like a pitcher or water dispensing refrigerator. But no matter what filtration option you choose, the search for the right solution should start by learning about your local water quality, the many different types of filtration technology and identifying what your family’s needs are when it comes to water quality.
Water Treatment System Standards
Even though water treatment products are regularly found in homes now, there are no federal regulations for these household water treatment products. However, the National Sanitation Foundation (NSF) developed voluntary standards through an independent product testing, inspection and certification process. As an organization accredited by the American National Standards Institute (ANSI), the NSF developed protocols that establish minimum requirements for the safety and performance of products designed to treat drinking water.1
Some NSF/ANSI standards are specific to a particular treatment technology. For example, NSF/ANSI 58 is specific to reverse osmosis filters. Residential water treatment systems can also be certified to multiple standards depending on the types of filters they use and the contaminants they’re certified to remove. Just because a filter, purifier or treatment system is certified to a particular NSF/ANSI standard, it doesn’t mean it’s been certified to remove all the contaminants under that particular standard. Therefore, it’s best to review the contaminant claims list for a particular residential water treatment system to see which contaminants the filter is certified to remove.
To learn more about specific treatment products, you can use this Water Quality Association tool.
What are Reverse Osmosis Systems?
Reverse osmosis is a water purification technique that uses a semipermeable membrane to separate ions, larger molecules and contaminants from pure water molecules. The semipermeable membrane is designed to let pure water molecules pass through, but not molecules that are larger than water.2 This leaves you with fresh drinking water on one side and concentrated contaminants on the other. Since reverse osmosis membranes can be damaged by exposure to chlorine and other substances, reverse osmosis systems include pre-treatment filtration steps like activated carbon and particle filtration to remove potential foulants.
During pre-treatment, the system can remove sediment and particulates, chlorine, scale-causing compounds, and even some pesticides and bacteria. Reverse osmosis systems are also effective at reducing Total Dissolved Solids (TDS), which are any minerals, salts, metals, cations, or anions dissolved in water.3 These solids can have an impact on the taste of your drinking water, with a very low TDS leading to a “flat” taste and a very high TDS leading to a “salty” taste. The EPA recommends that TDS in drinking water be less than 500 mg/l.4
Reverse osmosis membranes also often include post-treatment filtration steps. Since reverse osmosis removes beneficial minerals from drinking water such as magnesium and calcium, a mineral cartridge is often included post-filtration to add some of these important minerals back into the treated water.5 Despite its thorough filtration, there’s a limitation on how much pure water can be recovered through reverse osmosis membranes. In average household systems, anywhere from 3–25 gallons of water are wasted as reject water and sent down the drain, for every 1 gallon of pure water recovered from a reverse osmosis system.6 There is a wide variety of reverse osmosis systems available, from countertop to whole-home systems, so it’s important to explore the pros and cons of each type before buying a new filtration system for your home.
