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R.I.P. - Merlin Tankless RO System

by Mark Timmons October 06, 2010 11 Comments
Merlin by GE

Pentair mercifully "killed off" the Merlin Tankless Reverse Osmosis System effective October 1, 2010, finally doing what I have been saying needed to be done for 5 years. It was a tankless (and thankless) RO system which was supposed to make 700 or more gallons a day, never mind that the water quality ranged from "horrid" to "bad" many times. It was supposed to make Reverse Osmosis Systems with tanks obsolete, never mind it didn't shut off sometimes and continually ran water down the drain. The Revolutionary product first introduced by GE called the Merlin is now dead!

This is a classic case of over-hyping a new product by a large company. After millions of dollars of development costs GE was determined to recoup some of these expenses and went to market with a product known to have a high failure rate. After the Pentair merger, the product became a liability and Pentair was loathe to continue marketing a product prone to such high failure rates (we estimate up to 27% of the units fail within the first year). GE's self-proclaimed " Biggest Innovation in Home RO Technology in 30 years!" should have been called the "Biggest Flop in Home RO Technology in 30 years" but there are other candidates for that honor, past and present, and it remains to be seen whether Next-RO might also be a candidate. More on that soon.

If you are thinking of buying a GE Merlin (or Pentair Merlin) Tankless reverse, all I can say is you are buying an obsolete product if you buy the Merlin Tankless RO System. Think long and hard before you buy ANY tankless RO system - any and all are rife with issues. Pentair will continue to provide parts, filters and membranes for the Merlin Tankless Reverse Osmosis System for five years (ending October 1, 2015). All I can say is "I told you so."

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October 07, 2010 Norm

Just stumbled upon this discussion as i just inherited a Merlin filter from my father and was looking for output pressure specifications. so much for that!

I am looking to run a small commercial ice machine (350lb per day head unit) off a RO system so i need the output water pressure at least 25psi with roughly 35-40 gallons of water being used a day. Would this PERMEATE PUMP be an option for me?

October 08, 2010 Paul Trafas

Hey Mark,
I concur with your comments about the Merlin. They really did suck. As for the Next-RO, you’ve got to try it. I’ve put in about 30 units in the past few months and I tell you, after 26 years in the business it’s the best thing I’ve ever seen in the RO world

October 10, 2010 mark


I HAVE tried the next-RO. I bought two several months ago and have one in my home and the other at the office. I do have to say that the product is interesting, but the results have been less than stellar. I will be taking it out of my home soon and putting back in my permeate pump RO which beats the socks off of it in production, pressure and water quality. I am not a fan…

October 11, 2010 Tim

Mark I understand you tried the Next-RO engine and that you are not a fan of it! To each his own. Can you shed some light on the topic to me directly as to what your issues are. Is it not half the size of your system with the permeate pump? Does it make the clicking noise of your permeate pump? Does it not dispense an even flow all the way to the last drop unlike the permeate pump?

I would like to talk with you about your experience with the Next-RO engine ASAP

October 12, 2010 Peter

Does anyone know if the reconfigured version of the merlin I think known as PRF-RO distributed by Pentair still available?
I can’t find any refernece to it on the pentairaqua site.

Is it any good or does it have the same issues as the merlin?

October 15, 2010 mark


I would be glad to address your questions. I have tested the Next-RO is both my office and home for over 60 days. At the office, it was apparent that it did not produce nearly the pressure of the permeate pump RO, and that the flow was less than half of the flow from a permeate pump for the first 1.5 gallons (after that it was about the same as it tapered off. The incoming TDS is 476 PPM and the TDS from the Next-RO fluctuated on an hourly basis, from a low of 48 PPM to a high of 96 PP.

At home, I replaced a Permeate Pump RO with a 75 GPD Membrane. It is hooked up in the basement (on a shelf, close to the joists) and feeds two sinks and two icemakers. When I initially changed it, I did not tell my wife or son and immediately they both asked “What happened to the pressure?” Both complained that it tasted bad, but I personally could not tell the difference. Maybe that was just psychological due to the lowered pressure.

My incoming TDS at home is 688 PPM. For the first month it was installed, the TDS varied as much as 50 PPM on a daily basis. On a good day it was 64 PPM and went as high as 112 PPM. I tested it several times a day and it was always in that range.

About a month ago, the TDS suddenly dropped, and is now between 33 PPM and 56 PPM. I have found that if I take TDS readings when I first turn it on until it stops, that it will fluctuate up and down between 33 and 56 throughout the flow.

It has also failed to come on three times. I simply jiggled the faucet and it started making water and was OK after the tank refilled (this happened after I emptied it the night before). It hasn’t happened for a few weeks. We use a lot of water, probably 5-6 gallons a day.

Another issue I have had is that it the flow has been poor, but has operated my icemakers with no issues. It takes 45 seconds to fill a coffee pot. The Permeate Pump filled it in 16 seconds.

Maybe it would perform better if it were 5 feet higher and under my sink, but I’ll take the clicking (not that loud on the new pumps) of the permeate pump over the weak flow stream of the Next-RO.

It is small and maybe it’s viable for smaller applications, but I remain unimpressed with the flow and the fluctuations in TDS. It’s an interesting product – maybe there’s a “tweak or two” that can help.

It does dispense and even flow almost to the last drop, but I’m willing to bet I can fill a gallon pitcher 3 times faster with the permeate pump RO.

Feel free to call me at (317) 271-8600. I bought the systems from you.

October 17, 2010 Tim

Mark thanks for your detailed report it had been determind that our membrane supplier was using a very flexible tape for their brine seal causing the brine seal to flip on it’s seat. this would cause an intermitten flow and a periotic over concentration of the feed to the membrane. As per our conversation we will send you a new membrane.That should take care of this issue.

The pressure tank type RO systems with a permeate pump will give a huge flow rate given the fact that the pump brings the tank pressure to almost line pressure. This is an excellent flow and in most installations too much for an effective post treatment. The flow will be too fast to be effective. Faster is not always better!

Now that being said the basement installation is a normal installation in the mid west representing a fraction of the overall field of installs. Normally a typical install is under the sink where the Next-RO excells being half the size.

Lets see where this goes with the new membrane thanks for your comments

October 19, 2010 mark


It is being distributed by a couple of companies. I wasn’t interested, so I don’t know who they are. You could call Pentair and find out. The system is just flawed and we won’t handle it.

Things that sound too good to be true usually are….

October 21, 2010 jay

I am looking for a reverse osmosis system that will output 1 gallon of water (tank or tankless) at 0.5 gallons per minute at a constant pressure for a continuous flow rate again lasting for at least 1 gallon. I am operating a water ionizer that outputs 9.92 Ph water at exactly 1.5 liters per minute, only need a gallon at a time (my daily intake). Any ideas?

October 23, 2010 mark


They don’t make a RO system that will do what you want AND will deliver good quality water. It’s simply not possible with today’s technology. The Merlin tried and failed miserably. The water quality was horrific.

This system will give you the water in quantities and quality that you want:

October 26, 2010 Bob Black

notice that the next RO went the same route as Merlin.. trash can.

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