The Truth About Permeate Pump Reverse Osmosis Systems

The Truth About Permeate Pump Reverse Osmosis Systems
Posted in: Reverse Osmosis
By Mark Timmons
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The Truth About Permeate Pump Reverse Osmosis Systems

At US Water Systems, we have been believers in Permeate Pump Reverse Osmosis Systems for over 10 years now.  With several thousand permeate pump reverse osmosis systems in the field, we believed we were experts on these types of reverse osmosis systems.  However, over the past year or so, we have become somewhat disillusioned with the permeate pump reverse osmosis system because we have had mixed results, primarily with poor water quality. Case-in-point:  I always try different reverse osmosis systems at my home and after trying the nextRO for several months, I replaced it with a permeate pump reverse osmosis system (50 gpd membrane).  For your information, my TDS (Total Dissolved Solids) are around 540 ppm.  After 8+ months, I was really discouraged because my TDS routinely remained at over 100 ppm.  If I drained the system on back-to-back days, I could get it down below 50 ppm, but it would rise quickly again. TDS creep was winning the game.  In case you don't know what TDS creep is, it is defined as follows:
"The natural diffusion of TDS ions through the membrane from the feed side to the permeate side when the feed pressure is shut off (i.e., when the tank is full).  This effect results in lowered water quality."  A Practical Application Manual for Residential, Point of Use Reverse Osmosis Systems by Robert Slovak
Now, before we go any further, it needs to be understood that a permeate pump reverse osmosis system should do the following:
  1. A Permeate Pump RO should make water faster than an ordinary RO
  2. A Permeate Pump RO should make higher quality water than an ordinary RO
  3. A Permeate Pump RO should waste about 80% less water than any ordinary RO
  4. A Permeate Pump RO should deliver the highest pressure at the faucet of any RO
Well, my pressure was good.  Excellent actually, as I was feeding two ice makers, a kitchen faucet and a humidifier.  It makes water very rapidly and I know that it wasted less water, but the water quality was horrible.  Additionally, we have several customers who were not thrilled with their water quality, just as I wasn't.  What to do.... Everyone told me that the Aquatec 1000 Permeate Pump was the "cat's meow" but the results were less than stellar.  After months of fighting this issue, I decided to try the "old Aquatec 500 Series Permeate Pump" which is designed for membranes up to 50 GPD.  Not a 75 GPD or a 100 GPD, but just a 50 GPD. So, I changed the permeate pump ( a 2 minute job).  Then I drained my reverse osmosis tank (the TDS was reading 114 ppm). When I got up the next morning I checked the TDS and it was 18 ppm!  From 540 ppm to 18 ppm... not bad. It has remained below 25 ppm since then and we have made a decision at US Water:  We sell a 50 GPD permeate pump with an Aquatec 500 Series Permeate Pump, not a 1000 Series. Here's what bothers me: Why can't the engineers at Aquatec (who makes the permeate pump) and Watts (who USED to make our permeate pump RO system) figure this out? All 50 GPD Permeate Pump Reverse Osmosis Systems from US Water now have the Aquatec 500... and exceptional water quality. This is a public service announcement brought to you by The Water Doctor! Oh... the 500 is also quieter than the 1000...  duuuuhhhhhh!
November 8, 2011
Comments
craig
June 5, 2012 at 10:44 PM
I have a 5stage reverse osmosis system. The water pressure at my faucet is low and dripping at the water dispenser at the refridgerator. It takes about 10minutes to full a regular glass of water at the fridge. I bought a Aquatec 500 series permeate pump and installed it per the instructions but the water pressure remains low. What's happening? Help. - Pressure at tank is 20psi full 7.5 empty. - Pressure from sity water is just over 60psi. Thanks in advance for your reply. The Water Doctor Responded: Craig, It is going to take a process of elimination to solve this problem. Here's what you need to do first: 1. Drain the system completely and see if the tank still has water in it (you can do this by simply lifting it). It it does, the tank is bad and needs to be replaced. 2. There should be approximately 5 pounds of air in the tank when it is empty. Use a good air gauge to confirm this. 3. Your filters could be plugged - replace them and see if that makes a difference. 4. Your membrane could be bad, replace it. 5. Is your drain line plugged shut? 6. Your drain line flow restricter, check valve or ASO (automatic shutoff valve) could be bad. Replace them. 7. The Permeate Pump could be hooked up wrong. 8. The final things is that your pressure could be so low, the water temperature could be so low or the TDS could be so high, it will not work. That is about all that can be the problem. Good luck in your process of elimination.
Connie
February 5, 2013 at 12:25 PM
I am just learning about ro/di systems, since I never needed ro water before for my freshwater tank. According to this article, it's recommended that a 50 gpd system be used with the aquatec 500 permeate pump. What I am confused about is whether a 50 gpd system would be sufficient for weekly 50% water changes in a 75 gal. FW tank? I was recently told by an ro seller that I'd need a 300 gpd system for this tank! Can you advise? I am interested in a permeate pump ro/di system because I am on a private well and would like to waste as little water as possible, especially during drought times! Thank you!
mark
February 6, 2013 at 12:51 PM
A permeate pump RO is about 25% efficient in that it recovers 1 out of 4 gallons. A 300 GPD system is approximately 40% efficient: https://www.uswatersystems.com/us-water-300-gpd-floor-mount-light-commercial-ro-system-with-20-pre-filters.html but a 500 GPD US Water RO is up to 75% efficient: https://www.uswatersystems.com/us-water-500-gpd-american-revolution-commercial-reverse-osmosis-system-ar-4-500.html
Destitude
July 14, 2013 at 12:34 AM
How do you keep these systems from going bad? I have to replace my Aquatec 500 pump every 8 months. They are also manufactured to make it impossible to clean or fix whatever internal problem it has when I have to replace it every 8 months.
Ezra
December 1, 2013 at 9:56 AM
So what about your Aquapurion 100 GPD High Pressure Permeate Pump RO | APRO-5100-P-14? Does it occur the TDS creep? Please let me know. Thank you
Mark Timmons
December 2, 2013 at 2:11 PM
Yes it will if you don't use a lot of water and/or drain it once a week. The purpose of that system is for people who use a whole lot of water. If you don't have a high demand, use a smaller one. If you use 15+ gallons a day, the TDS Creep will be mininmal.
Ezra
December 31, 2013 at 10:01 PM
Hi, May I know the ideal pressure switch's setting is?( 40psi, 60psi or 80psi ) I run my RO unit with Hydronamic's High Auto shut off valve with permeate pump (Shuts OFF at 87% of feed pressure and Turns ON at 77% ) and now would like to buy one 6800 booster pump, so which PSW ( psi ) should I use? please advice! Thank you
Steve
January 31, 2014 at 8:27 PM
I have a RO with a ASO valve. If I add a permeate pump - can I delete the ASO valve?? Some manf set up diagrams sho wit with a ASO valve and some show without an aso valve Thank you
Mark Timmons
February 1, 2014 at 1:14 PM
That is the way we make our Permeate Pump RO systems. The ASO limits the effectiveness of the Permeate Pump. If it were me, I would do it without the ASO.
Jim Baker
September 15, 2014 at 11:55 AM
I have a 100 GPD rated RO unit. However our water usage is limited. I am thinking about adding a permeate pump to increase water pressure at a location upstairs. I would like to use the ERP 500 rather than the 1000 as it supposed to operate quieter. Is the rating of the RO membrane that determines the size or the actual water usage. Will the ERP 500 work for my purposes?
Mark Timmons
October 17, 2014 at 1:47 PM
The 500 will only work on membranes up to 50 GPD, while the 1000 works on membranes up to 120 GPD.
Rich
December 27, 2014 at 6:23 PM
Pereate pump with ASV, or no ASV: I have had great success using an ERP100 on a 24gpd system, without an ASV. I love the high faucet pressure, the Aquatec controlling the shutoff function. At another location, I built a 50gpd system, with another ERP1000. This system took much longer to recover the tank (system was running too often, too long). I decided to install a 90% ASV, rather than the standard 60%. This did solve the constant running of the system, but I am not happy with the pressure. Are there inherent inconsistencies from ERP unit to unit? Should I go without an ASV and try again?
Mark Timmons
January 15, 2015 at 3:07 PM
With a 50 GPD Membrane, you should use the ERP 500. Don't use the ASO and you will have excellent pressure.
Aaron
May 29, 2015 at 10:48 AM
I am experiencing what you describe here. I have a 5 stage 90 GPD system. It was producing 13 TDS water. After adding the ERP 1000 and waiting a few weeks (I didn't drain) it is producing 62 TDS water. I don't fully understand TDS creep though, so that may be part of the issue. Should I downgrade to an ERP 500? We don't use much water.
Mark Timmons
June 1, 2015 at 8:24 PM
Go to a 50 GPD membrane and 500 and it will be great. Be sure and change your flow restrictor.
Bob
September 17, 2015 at 1:56 AM
Just installed an ERP-500 and my TDS doubled. It's coming out now.
Mark Timmons
September 17, 2015 at 8:28 PM
The only way that can happen is that you are not using much water. Try draining the tank every day for a few days in a row and see what happens to the TDS. A permeate pump is not for someone who uses very little water.
Patrick Doan
March 27, 2017 at 9:03 AM
Is absolute TDS a good measure of the performance of the RO system? We bought the system you describe in the article above - because of the article above - and our TDS from the RO system is around 66 ppm. That's great considering the incoming water is around 578 ppm, but, based on this article, matching the Aquatec 500 Series permeate pump with the 50 gpd RO system, I was hoping for something more in the 20s.
Mark Timmons
March 27, 2017 at 11:16 PM
Here's something you should know: Once a week, drain the tank of the RO completely and let me know hat the TDS is then.
Leland
May 18, 2017 at 3:45 PM
I just bought a system that came with a pressure pump. Should I still install a permeate pump?
Mark Timmons
May 22, 2017 at 12:49 PM
That would be up to you, but it it is set up right, it may not be necessary.
Steve N
July 16, 2017 at 6:25 PM
HI My RO tank Pressure with Permenate pump (ERP500)is only 22 pounds (well pump 40-60 range 50 ave#) With 90% Aso it about 28 pounds. My TDS=409 RO tds=40 Water flow is low to ok IF I wanted more pressure what do you suggest ?? - prepump set to 80# intake -eliminate the ASO ? when you talk about no aso and tds creep how much additional tds are you looking at ? 10% increase? - Thanks
Mark Timmons
July 16, 2017 at 9:39 PM
You should have no more than 5-7 psi in your RO tank with it empty. Eliminate the ASO. It is counterproductive with a permeate pump. If you drain your tank once a week, there will be no TDS creep.
Adeline Parson
November 7, 2017 at 1:12 PM
We are looking for a solution because we purchased a Radiant Life 14 stage water purifier which use RO as one of the stages. It wastes sooooo much water and we haven't figured out an easy way to capture and reuse the water efficiently and without a big chore. Do you have any recommendations or suggestions. We have a front load washer so we cannot run a hose to the washing machine and at the rate it pours off the water, it seems a washer would overflow anyway.
Mark Timmons
November 9, 2017 at 12:30 AM
I do not understand why the washer is somehow involved. By the way, that "14-Stage Water Purifier" is a bit of a joke in my opinion.
Omar
December 17, 2017 at 3:45 AM
I have a 5 stage 50 gpd system. I had an ERP-1000 and was getting a 50 tds reading from the tank (input 260ppm). Seemed high, so i switched to ans ERP-500. Initial reading was 19ppm direct bypassing tank. After 1 or 2 days, my tank is showing 50ppm again. Getting frustrated with this. Assume its TDS creep as we dont use a lot of water. Is it time to dump the permeate and try a demand delivery?
Mark Timmons
December 17, 2017 at 2:35 PM
I have a permeate pump RO in my house and have for years. My incoming TDS is 480 ppm. Every Sunday, I drain the tank and my TDS stays below 30. If I don't it will creep up to 50+. If you don't use a lot of water, it is essential you flush the tank regularly.
Omar
December 17, 2017 at 3:16 PM
Thanks Mark, would I still be getting TDS creep if i removed the Pump and put the ASV back on? Are those 90% ASV worth it? The whole point of the permeate pump for me was to get pressure to the fridge so the icemaker/water dispenser would work.
Mark Timmons
December 17, 2017 at 4:31 PM
Adding an ASO totally defeats adding a permeate pump. Just drain the thing once a week. 90% ASO=Fiction
Dave Rzonca
December 28, 2017 at 11:23 PM
Mark, I installed a 5 stage 75gallon reverse osmosis system in my home. My TDS in is 1168(well water) and my out averages 75TDS. I drain my tank every few days and it seems to help the TDS creep, keeps it under 95. Is there anything else I could do to get my tds lower? Thanks,
Mark Timmons
December 29, 2017 at 11:00 AM
You need a booster pump. Higher pressure will give better rejection, as as rule: https://www.uswatersystems.com/aquatec-cdp-6800-booster-pump-with-transformer-switch.html
Brett Blitzstein
January 5, 2018 at 2:55 PM
I am totally new to all of this. I am about to install an iSpring RCC7AK 6-Stage 75GPD system. I also will tee it off and run a line to a water dispenser with hot and cold (Brio CL3000U). I also ordered a Aquatec 1000. But am I going to ruin the pressure to the dispenser? And I saw one comment somewhere about removing the hydraulic pump from the permeate pump if you're running water to an ice maker. I don't even know what that means. And would the demand for pressure be the same for a dispenser as it would for an ice maker? My dispenser has a 4 liter tank for the cold and 2 liter for the hot. I think the flow rate of the water through the dispenser, though, comes from the pressure in the system and not gravity. So what do I do with the permeate pump and where do I put it? Am I going to screw up the pressure to the dispenser? Help please.
Brett
January 6, 2018 at 10:41 AM
Hi, I've ordered an iSpring RCC7AK with remineralization alkalinizing stages, and also an erp 1000. I don't know what constitutes "low usage" on whether or not to eliminate the ASOV. I have a family of 5, so I'm assuming that I will NOT have low usage and will in fact eliminate the ASOV. Am I to put the Permeate pump after the RO stage and BEFORE the mineralization and alkalinizing stages? Any links to diagrams? And I will be teeing it off to a hot/cold water dispenser. Where do I put the tee? ?? Off the final line to the faucet? And from reading (and reading and reading) it seems ice dispensers need a certain pressure to work, but NO ONE that I can find is using a water dispenser, but I believe it too will benefit from extra pressure. Any further advice is appreciated.
Mark Timmons
January 7, 2018 at 10:47 AM
I have to ask "Why are you buying and iSpring and coming to us for advice?" Maybe their system is a little cheaper but RO's with Chinese filters are always cheaper. You should search re-mineralization and alkalinity on this blog. It's a waste of money in my opinion.
Brett
January 6, 2018 at 11:15 AM
ok, Found good diagrams here: https://www.uswatersystems.com/pdf/PermeatePumpManual.pdf
joe
January 11, 2018 at 6:25 PM
Since the ERP 500 is a quieter newer pump, can I use the ERP on a 750GPD system? What would happen? Thanks Joe
Mark Timmons
January 12, 2018 at 10:51 AM
You cannot use it on a 750 GPD System.
Dave Rzonca
January 31, 2018 at 1:09 PM
Mark, Thank you for your reply & suggestion on how I can resolve my performance of my system. I will be ordering this thru you.
J Miller
April 5, 2018 at 3:55 PM
Just wondered what is considered low water usage a day?
Mark Timmons
April 9, 2018 at 3:11 PM
Maybe a gallon or less..
Dave B
April 29, 2018 at 10:11 AM
Hi Mark, Why can't you use the ERP 500 on a 75 gpd system? Did I screw up as I just added an ERP 500 (due to noise) to the existing RO system that was in place when we bought the house. I installed it per your diagram without the ASV and all is improved. TDS is 17ppm from 540ppm with better pressure and recovery. After further research into the system I discovered it has a 75gpd membrane. Must I change the membrane or the pump? Will it ruin the membrane or the pump if left as it is? Any information would be greatly appreciated. Thanks, Dave
Mark Timmons
May 1, 2018 at 7:17 AM
You can. You just can't use a 100 GPD membrane on an ERP 500.
Eric Epperson
June 13, 2018 at 1:33 PM
I have a 90 gpd system with no pump that works great at the to tap, but the fridge water is mind numbingly slow. The ice is making just fine. At the risk of sounding very ignorant... Why couldn’t I install a pump after the ro system to boost pressure to the fridge? Wouldn’t that eliminate the “creep” issue? Is there something I am not taking into consideration that would cause an issue with the system?
Mark Timmons
June 13, 2018 at 6:32 PM
You could - just make sure you have enough water storage in the tank.
Greg
August 27, 2018 at 5:39 AM
Wow, what great info here! So, to be clear, If one deletes the ASO does that mean the P/P will immediately run even dispensing a pint of filtered water until tank is topped off again?
Mark Timmons
September 3, 2018 at 5:46 PM
Yes, it does it with the ASO too.
Ananda Tracy
September 27, 2018 at 10:14 AM
I had a similar problem that completely baffled me for quite a while after I installed a permeate pump on my existing reverse osmosis System. At first it seemed to work really well. The TDS dropped from 32 to 18 after initially installing the pump. However, after a month, the TDS went back up to 250 - 300. I tried replacing all of the filters twice in two months because I thought that high TDS could only mean a bad RO filter that has already been damaged by Iron and rust. However, after re-reading the permeate pump instructions very carefully, I noticed that I did two things wrong: the pump was upside down (the outlets have to be on top for the air to escape when you bleed it after its first installed), and the flow restrictor was after the pump, not before. After correcting both of those issues, the trapped air cleared the pump and the TDS went from 300 to 42 overnight. TDS Creep was caused by my malfunctioning permeate pump, allowing the TDS to rise above 300.
Mark Timmons
October 1, 2018 at 9:57 AM
Yes, it is important to have the pump positioned with the outlets in the right position.
Richard Schwarz
October 22, 2018 at 6:38 PM
Mark, We just moved in to a new place and want to install a whole house system. If the average daily use per person is 80-100 gpd, is it possible to install multiple 50 gpd systems in series, or ?, to produce up to 200 gpd of high quality water? And, when guests are present the demand goes up. What happens to the quality based on higher demand, if any? Thanks for your counsel.
Mark Timmons
October 23, 2018 at 2:13 PM
I guess you could buy 30 mini-vans and hook them together to pull a semi trailer... or you could just get a semi tractor and it would do the job better and more economically. Additionally, a 50 gpd RO would waste` 3-4 gallons for every gallon made, while a commercial model would waste as little as 1 gallon for every 4 gallons made. Actually, doing that would be a vert bad... and wasteful idea. It woulkd likely take 50 to 75 systems to do what you need. Our new "Defender" Whole House RO systems start at $5,995.00 and will work for years.
David
March 3, 2019 at 2:43 PM
If one was to use a Permete Pump as well as an electric pre filtration pump, would this further increase efficiency and flow, or either?
Mark Timmons
March 6, 2019 at 5:32 PM
Sure, you would have higher pressure coming out.
Mike Weiss
September 14, 2019 at 11:19 PM
I have one of your permeate pump RO systems and have always disliked the noise it makes. I read the article about using the smaller pump for better water quality and less noise, can you tell me how much the smaller pump costs so I can get that on my next filter order? Is it a good idea to just buy a whole new system every few years in cab bacteria is starting to infect it? I find the sanitation process easy to screw up, and no way to test it's effectiveness...Mike
Mark Timmons
September 15, 2019 at 7:32 PM
If your system has a 50 GPD membrane, it probably has the quieter pump already. It's not "smaller" just quieter but won't work on a membrane larger than 50 GPD. I suggest replacing the tank every 4 or 5 years and also using this: https://www.uswatersystems.com/us-water-pulsar-quantum-disinfection-cartridge-for-ro-systems.html?quantity=1
Darrel Rowell
October 29, 2019 at 8:34 PM
"We sell a 50 GPD permeate pump with an Aquatec 500 Series Permeate Pump, not a 1000 Series." Not sure I understand this statement. Gonna guess you meant a "50 GPD RO system". Also, were you using the Aquatec 1000 permeate pump with your original 50 GPD membrane system? If so, is that ok to do? I have a 100 GPD membrane on my system and am wanting to install a permeate pump. I am assuming that I should have a 1000 series permeate pump to go along with that and, as you stated, not a 500 series. So, in short, is it OK to have a permeate pump that can handle less than your membrane is rated for but not more? Do you think the 1000 is junk?
Mark Timmons
October 30, 2019 at 8:18 AM
No, it's just very loud... maybe not quite as reliable as the 500 but necessary with the 100 GPD Membrane.
Gordon Saksena
December 8, 2019 at 6:01 AM
Is it possible to make the ERP 500 work with a 90 GPD membrane by messing with the flow restrictors? Eg replace the 700cc restrictor that came with the membrane with a 300cc restrictor normally used for 50GPD membranes? Or, T the membrane waste output into two lines, each with a 300cc restrictor, and run one of those through the permeate pump?
Mark Timmons
December 22, 2019 at 6:04 PM
It might work, depending upon your water quality, but I would not recommend it.
Gordon Saksena
December 22, 2019 at 6:04 PM
I tried using an ERP 500 with a 90GPD membrane, and it appears to work... Without the pump, drawing 10 cups of water from a full tank produces 120 cups of waste water at 600 ml/min over 50 minutes, and with the pump it produces 50 cups of waste water at 550 ml/min over 30 minutes. The (70%?) ASO valve was left in place for this, so the final tank pressure was the same in both cases. From reading, I would expect only 25 cups of waste water from the ERP 1000 for this setup. So, perhaps this reduced wastewater efficiency is the reason the ERP 500 is not recommended for the higher GPD membranes. Another observation - when I added a 300 ml/min restrictor to the waste water input to the pump, like how it was meant to be used, it output water about 50% of the time - 3.5 seconds on (flowing), 3.5 seconds off. When fed with just the 600 ml/min restrictor, it was more like 25-30% off, eg 3.5 seconds on, 1 second off. The off time must be when the pump is using the water pressure to wind itself up. I will assume the ERP 1000 would have closer to a 50% off time for my system, making it a more powerful pump.
Ulrich Gauthier
March 8, 2020 at 4:04 PM
I am on well water and a booster pump installed, and wasting lots of water can I install ERP 500 permeate pump to my 6 stage system?
Mark Timmons
March 15, 2020 at 12:32 PM
Yes, you can.