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Reverse Osmosis and Icemakers

by Mark Timmons August 28, 2009 19 Comments

First of all, you can make ice cubes from water produced by reverse osmosis systems. In fact, ice made from reverse osmosis (”RO”) water produces cleaner, clearer and better tasting ice cubes because most of the contaminants are removed from the water. So, just because water is purified by a certain process, (in this case, reverse osmosis), has no bearing on whether you can make ice. I prefer “clean ice” - in many cases it is perfectly clear, except for a little cloudiness in the center of the cube. Another benefit is that the cube is harder and melts slower. Most people like that as well. So, why would an ice machine technician tell you that RO water won't work on an ice machine? I suspect that his experience is that he has seen many situations where he is called on a service call and found that when the reverse osmosis system was disconnected and the ice-maker was connected directly to the house supply, it worked. That doesn't mean that RO water won't make ice cubes, however.

When you supply an adequate volume of water at an adequate pressure, any ice-maker will produce excellent cubes. The problem with an RO system on ice-makers (especially the “basement bar-type” machines) is that those types of ice machines use a large amount of water. Believe it or not, some of those machines can use 80-90 gallons of water a day! Unless you have a high volume reverse osmosis system, it is futile to try and supply RO water to that kind of ice-maker. Another issue is pressure. Many new ice machines require 30-40 PSI (pounds per square inch) to function properly. A residential RO system drops the incoming pressure by 30-35% If you are starting out with 70-80 PSI, that is acceptable, but if the incoming water pressure is 40-60 PSI, there may be a problem. Volume and pressure are separate problems. You may have enough pressure to operate an ice machine, but not sufficient volume and it's not as simple as adding another tank with plenty of volume and little pressure. Sizing a reverse osmosis system is critical when you have multiple outlets, especially if one or more is an under-the-counter ice-maker. Most residential reverse osmosis systems are 24 to 50 GPD (gallons per day), which is not nearly enough for such an ice-maker. Additionally, production is reduced whenever the water temperature is below 77 degrees F, and whenever the pressure is below 60 PSI.

In the real world, a 50 GPD reverse osmosis system in the Midwest may produce 20-25 GPD, when the demand may be up to 150 GPD. There are solutions, and they do not have to be extremely expensive. One solution is to install a larger system, such as a 300 GPD system or a high production system, such as GE's Merlin system, which produces 1/2 GPM of RO water. Another solution is to boost the incoming pressure with a booster pump or boosting the system pressure to 80 PSI with a Demand Delivery Pump. This type of system will provide plenty of high quality, great-tasting RO water, without running out! So, you can use RO water on ice machines (we install RO systems on very large commercial machines). They just have to be sized properly.

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March 18, 2016 Mark Timmons


April 29, 2017 Damir Valjak

Hi! I have a 3 ton/day ice machine. How big does my RO system have to be? Would 800 GPD work? Tnx

April 29, 2017 Mark Timmons

I ton of ice = 240 gallons… not counting what you waste. So a 3 ton machine would use about 750 gallons (maxed out), not counting the water that is wasted. A 800 GPD RO system makes 800 GPD IF it runs 24/7 which is not good for longevity of the system. Also, for every degree below 77 degrees F, you lose 2% efficiency. Ideally, if it were me, I would use a 2,000 GPD so that the system does not have to work it’s head off.

August 04, 2018 Tyler

I have a 500 lb ice machine. At full capacity it would use just under 100 gallons per day. Rarely will the machine ever need to make more that 200 lbs in a day, so usually 40 gallons a day would be max water usage. I am looking at The ice machine calls for 20-80 psi water supply, will this RO system be able to provide that?

August 05, 2018 Mark Timmons

It can provide that, but you have to remember that this is a “Light Commercial” RO system. You will have much more longevity if you use a 500 or 600 GPD system.

December 27, 2018 joe

can I increase my ro system which is 7 psi on my storage tank to get more water to my ice maker

December 27, 2018 Mark Timmons

No, you will need to add a pump.

November 07, 2019 Diane

I bought an under the counter Scotts icemaker and know that I need to use reverse osmosis because I have soft water. With the APEC seven stage RO system be correct to use with that icemaker?

November 10, 2019 Mark Timmons

You will need to find out how much water the icemaker uses. Many use way too much water for an RO like that. Give me that number and I can tell you.

October 08, 2020 RODRICK TAYLOR

I have a Apec RO-90 system and a Samsung Model #RF28N9780SG refrigerator. Will my RO-90 system be able to supply enough water to the ice maker?

October 08, 2020 Mark Timmons

I would suggest you contact Apec. We manufacture our own All-American Made RO’s. I really don’t know much about their quality or function.

March 01, 2021 Henry Brantingham

Does remineralizing RO water affect the quality/clarity of ice from the ice-maker?

March 14, 2021 Mark Timmons

It adds some TDS back, so depending upon the type of icemaker, it can make the ice a little more cloudy.

March 14, 2021 Henry Brantingham

Does remineralizing RO water affect the quality/clarity of ice from the ice-maker?

March 15, 2021 Mark Timmons

Yes, it can, depending upon the type of icemaker you have. You are adding minerals and TDS.

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