RO Filters and Tubing

randalls1April 9, 2012

Hi All,

A water softener is being installed on our well water system. We had our well water thoroughly analyzed by a state certified lab and the county board of health. We have applied the much appreciated recommendations we received from this site.

Part of the system is a new RO unit at the kitchen sink. It works fine, but I have just read that because RO water is so clean it can be very aggressive, thus plastic tubing should be installed. The pro plumbers who installed the RO system ran a 1/4" copper line a little over 30' long, from the RO filter's under sink storage tank, around the kitchen perimeter to the refrigerator for it's ice maker and cold water dispenser.

Is the copper tubing a problem? Do we need to test the water at the refrigerator to see if it has excessive copper, or other contaminants, from that copper line? Do we need to have the plumbers replace that copper line with plastic tubing?

Any and all replies are gratefully appreciated and hoped for.

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Copper tubing will absolutely be a problem - it will develop pinhole leaks, which sound small, but can absolutely ruin your house. Don't bother testing the water at the refrigerator; just have the plumbers replace the copper with plastic.

    Bookmark   April 9, 2012 at 12:46AM
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I'm surprised that a "plumber" would have done this.

Also, thirty feet is a pretty long run for 1/4". Since you're replacing anyway, might consider 3/8".

    Bookmark   April 9, 2012 at 9:24AM
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Just for kicks, googled "RO water and copper tubing" and found a number of entries. This is copied/pasted from one of them:

Can I use Copper Tubing for the RO Product Water?

No. Due to RO product water being very pure, it can leach the minerals from copper tubing which will cause a metallic taste in the water or ice, and cause the copper tubing to develop pinhole leaks over time.

How Far Can A Line Be Run From the RO System?

If using 1/4" Poly tubing: Approximately 20-25 Feet.
Use 3/8" Poly tubing for longer distances.

Tubing for RO product water should always be POLY tubing, not copper.

    Bookmark   April 9, 2012 at 4:04PM
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RO water was is considered 'aggressive'. I have seen RO water run through copper lines for many years and not have pinhole leaks (really depends on it pH) but nonetheless it is not recommended. Long before any leaks that may occur, copper will be leached from the lines and may leave a metallic taste and even a blue/green stain.

Water does one of two things: either it leaves behind contaminant deposits on surfaces (calcium/iron/sodium) or it leaches elements from surfaces over which it passes (corrosion). The 'cleaner' the water, the more likely it will 'leach' from those surfaces. Glass, ceramic, stainless steel and certain plastics have very low corrosion/leaching tendencies.

Whatever the philosophy, avoid running RO water through any metal lines, fixtures or containers as much as possible.

Andy Christensen

    Bookmark   April 9, 2012 at 4:17PM
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If you really want some interesting reading google Reverse Osmosis water & health risks.

    Bookmark   April 9, 2012 at 5:07PM
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Dear All,

Than you very much for your replies. I have never found a site as helpful as this one and whose members so freely share their knowledge and experience. And it does make a difference. I hope that one day I will be able to pass on the same favor of assistance.

I have contacted our plumber, a really well regarded company that stands behind their work, and shared what I have learned from this site, and this thread, via your kind replies. The company owner said he had never heard of the problem RO filters have with copper, but he will replace the entire copper line with Poly if that is what we want. It is. All's well that ends well.

To everyone who responded, thank you again and my warmest regards to all of you.

    Bookmark   April 9, 2012 at 10:33PM
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Thanks for coming back to say outcome.

Kudos to your plumber for standing up. That's good to hear.

    Bookmark   April 9, 2012 at 11:09PM
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"I have seen RO water run through copper lines for many years and not have pinhole leaks (really depends on it pH)"

The aggressiveness of RO water has nothing to do with pH.

It is entirely that the water is so clean it can pick up material from just about anything that can dissolve in water.

It is the same issue that has been linked to 'cleaner' water under the new EPA standards.

In normal use a stable coating develops on the inside of copper supply lines that limits further leaching of the copper.
If the water has very low total dissolved solids this protective layer cannot form, and can even be stripped away.

Adding orthophosphates back into the water cleaner than required water allows the coating to form, protecting the pipe.

The EPA has admitted that their own corrosion experts did not have input on the newest standard.

The left hand does not know what the right hand is doing.

    Bookmark   April 10, 2012 at 2:59PM
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As the almost perfect solvent, water will attract and dissolve whatever it comes in contact with that it can. The more that is stripped from water (by whatever means) the more aggressive the water will be at replacing that which was removed and not just RO water.

    Bookmark   April 10, 2012 at 3:52PM
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"...and not just RO water.


Even distilled water is aggressive.

You should see the damage condensate (essentially a cold distilled water) can do long term.

    Bookmark   April 10, 2012 at 5:57PM
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"You should see the damage condensate (essentially a cold distilled water) can do long term"

I have and that's why I said "...and not just RO water", but it's nice of you to repeat it.

    Bookmark   April 10, 2012 at 6:07PM
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Being a plumber I am not really worried about the effects of premature failure of a piece of pipe, I can replace that easy enough but in researching Reverse Osmosis I found dozens of reports on the health hazards associated with it.

During the 70's NASA studied the idea of using RO to recycle human waste to produce fresh water on long space flights, and the U.S. Navy conducted studies to determine the effectiveness of using RO to produce freshwater from seawater. The WHO (World Health Organization) and a half dozen top universities all over the world also studied the idea of using RO to produce safe drinking water in arid third world countries, and all of them came to the same conclusions.

Extended use of RO water has a twofold health risk;

1. There are a number of essential elements that we normally injest from our water, such as, but not limited to Iron, Calcium, & Iodine.

2. not only does the RO water not contain those essential elements, RO water is so aggressive that as it passes through the digestive tract it actually absorbs those elements from our food and carries it off in our waste. As if that is not bad enough, when RO water enters the body it absords those elements from the organs in our body, by example, it may absorb iron from the red blood cells reducing their ability to carry oxygen and it absorbs calcium from our bones and carries it out with our body waste.

But don't take my word for this, run a search on Yahoo or Google for "Reverse Osmosis Water & Health Risks" and read it for yourself.

    Bookmark   April 10, 2012 at 7:27PM
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and reason #3 was that at the scale the WHO was looking to provide potable water from seawater RO was too low a yield, too slow a yield, and far too costly.

To be fair... for anything one can Google in support of any position one can find equal information supporting the opposite view and about the same percentage of the info on the internet supporting both pro and con on any subject is bull.

Like pretty much anything ROs have their pluses and minuses. The trick is understanding exactly the environment and circumstances in which an RO may be installed and making an informed decision whether that meets the wants and needs of the people in that environment.

There are ROs and cartridge elements that will introduce selected minerals back into RO water after the undesirable elements and dissolved solids and other stuff have been removed by the RO membrane if that's what one wants.

As for me... 18+ years consuming only RO water and I'm still here. An added bonus is that my coffee maker, which makes GREAT coffee with RO water, is still here too and has never had to be decalcified

    Bookmark   April 10, 2012 at 8:06PM
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I'm certain my 100-year-old mother, with whom I live, and whom (not sure I've got the who/whom down yet) along with me, has ingested this poison for more than twenty years now, will be interested to learn about this.

What is certain where we live is that between the chlorine and alkali in the supplied city water it tastes terrible. After the RO it doesn't.

We're surrounded by mines. Water comes from that underground supply. I know what's in it. I'll take the RO, thankyou. Where I live, every household that has two nickels to rub together has a unit under their sink.

    Bookmark   April 10, 2012 at 8:19PM
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lazypup, what are you recommending for excellent drinking water?

    Bookmark   April 10, 2012 at 8:48PM
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A quick read of my best hit would have me avoid drinking a lot of RO water:

Rolling revision of the WHO Guidelines for drinking-water quality
Draft for review and comments (Not for citation)
Health risks from drinking demineralised water
By F. Kozisek

    Bookmark   April 11, 2012 at 3:06PM
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Wow, after reading all these posts I thought it would be a good idea to have a third waterline at the kitchen sink to supply untreated cold water. Our Calcium is 50.7 PPM, Magnesium is 10.0 PPM, TDS is 354 PPM, total Iron is 0.233 PPM and Total Hardness is 9.8 GPG. Both the Calcium and Magnesium are within the recommended range to provide some cardiovascular and other health benefits. So, next week our plumber has scheduled us to have the copper line from the RO filter to the refrigerator replaced with Poly and will be looking at installing a PEX water line from the main water line, before the softener, to the kitchen sink along with a second dispenser valve of some kind. Then we can drink either the untreated water, the treated water or just the water from the RO filter. The softener will ensure the new toilets and washing machine soap dispenser are not stained anymore and the showers and dishwasher are not clogged. The RO filter will ensure the refrigerator ice maker and water dispenser have clean water. The Poly line from the RO filter to the refrigerator will take care of the copper problem, metallic taste and maybe some green stains, and the soon to be untreated water dispenser at the kitchen sink will satisfy those in our family who now want to drink only the untreated, but healthful, well water.

How did this get so complicated? It's only water. My VISA card is melting.

    Bookmark   April 11, 2012 at 5:11PM
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Don't get too crazy. Just get decent water. Nobody lives on water alone.

Morarji Desai, once prime minister of India, drank their miserable water for his entire life and, somewhat famously, started each day with a 10-oz. glass of his own piss. He lived to be 99.

    Bookmark   April 11, 2012 at 6:31PM
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