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Current IssueSeptember 02, 2014
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Ask The Expert: RO choices
05/01/2004 
 
Question: Q: I’ve been trying to research reverse osmosis (RO) systems for the past several days to find one of the best available. It gets very confusing especially when trying to compare Water Quality Association (WQA) statistics with NSF International statistics and talking to the various organizations. To be perfectly honest it's giving me a headache. All I want is to find out what one of the "best" companies is to by an RO unit that will make water as clean as I can get it. Can you please help me?

Dave Hermanson
St. Louis, Mo.

 

Answer: 

A: Frankly, it depends on what you want. Do you want a countertop system, an undersink system or a standalone point-of-use (POU) cooler system? Typically, an RO will include carbon and sediment filtration. They can also include additional technologies for disinfection as well. Among popular franchises, you can try Culligan, Rainsoft, Kinetico, Ecowater, Rayne, Hague and Ionics dealerships. Any of them can provide a very good RO system to serve your needs. Many local independent dealers who may be members of the WQA can be just as helpful and might offer a more competitive price—as there are a number of very qualified independent manufacturers that supply them as well. A full listing can be found under “RO Equipment/Components” or “Reverse Osmosis” in the WC&P annual Buyer’s Guide, which comes out each April and is available online at: www.wcponline.com/BuyersGuide.cfm. You can use the WQA's "Find a Professional" function from its website—www.wqa.org—to find a qualified dealer near you.

To narrow your focus, you can ask questions about efficiency and recovery rates of the RO unit. In particular, you’ll want to know the ratio for how many gallons of water go to waste as concentrate or reject water in order to produce a gallon of purified water, also known as permeate since it has passed through the RO membrane. This is the recovery rate. There has been some work done at the WQA and NSF to clarify this information for consumers in product literature, so you’ll want whoever you’re speaking with to specify what the recovery rate of the system is when the unit is connected to a storage tank, as that offers the clearest real-life picture of how the system will operate. There are a number of “tankless,” “zero discharge” or “water-on-water” RO systems that have emerged in recent years that offer greater water efficiency with minimal water waste. On these, you may want to know about “TDS creep,” or the tendency for dissolved solids on the reject side to creep through the membrane into the product water under stagnant or storage conditions. An article that can help you understand this information can be found in our September 2001 issue: “Recovery & Efficiency: RO Water from POU Units—The Real Story,” by Peter and Tom Cartwright. If water efficiency isn’t so much a concern, you can do as I did and reroute the drain line for your RO system to water trees or bushes in your yard. Since this water contains concentrated dissolved solids, you’ll want to provide additional watering occasionally.

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