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Thread: Copper or PEX?

  1. #1

    Default Copper or PEX?

    I have read most of the old threads about pinholes in copper pipe and wonder if I have a problem with corrosive water and should replace the copper with PEX? How does a person figure out if it would be worth the considerable expence to replumb a house?

    House is 15 years old with copper all through, some of it is rigid and some is flexable but I don't know what scheduld the wall thickness is. Ten years ago I replaced a brass faucet assembly after crushing the brass trying to change a faucet valve. A plumbing store said I probably have corrsive water and should get the proper treatment system installed. Mainly because they were sellling the treatment systems I took the advice with a grain of salt.

    Five years ago I got one pinhole in a length of flex copper right in the very bottom of the pipe in the middle of a horizontal a run. I cut the section out and soldered in a replacement piece. I don't know what I am looking for but I couldn't see much interesting looking at the section I cut out. It got me wondering about what the plumbing store had said again.

    I had a analysis done on my well water and among other things it said my PH is 7.4 but the corrosivity is minus 1.1 on the "Langerlier Saturation Index". Report said a slightly positive number up to +2 is desired. So how bad is a minus 1.1?

    I tried to clean up any copper to galvanized connections, found one maybe. Recently I had some electrical work done and electrictian cleaned up a clamp on the ground rod which had rotten away; don't know how long it has been that way.

    I have just gotten my second leak somewhere up in the second story wall . I caped off the copper line to the showers but haven't opened the tiled shower wall to find exactly what was leaking. I am wondering if I should just fix the leak or should I be thinking of replacing all my copper with PEX or what? Code around here recently allowed PEX.

    Neighbors around here don't seem to be talking about pinholes in copper but maybe I just haven't heard.

    Would a treatment system be in order?

    Thanks in advance for any help.
    Last edited by Mike S; 12-26-2005 at 10:18 PM.

  2. #2
    Plumber Cass's Avatar
    Join Date
    Nov 2005


    Bob NH Or Gary should be able to tell you what the #s mean from the water test. It sounds like you may have had a bad ground causing the pin hole or maybe a combination of water quality and the ground.

  3. #3
    In the Trades Bob NH's Avatar
    Join Date
    Oct 2005
    New Hampshire


    Here is a link to a paper on corrosivity. http://www.water-research.net/corrosion.htm
    Your water is mildly corrosive on the corrosivity index. (Corrosivity Index - Langelier Saturation Index ). Negative numbers indicate corrosion while positive numbers indicate that there may be some scaling or deposition. Some deposition is beneficial because it protects the pipes.

    Do you have a well or public water supply? If a public water supply you may want to inquire what they are doing to minimize corrosivity of the water they deliver.

    Do you have a water softener? Very soft water is slightly corrosive and you might try to bypass a little past the softener. They are often installed with a bypass valve in the plumbing and you could open the valve a bit until you notice that the water is too hard, and then close it down a bit. It is not a precise control but a little hardness in the water usually makes it taste better and a little hardness won't hurt the shower or clothes washer. Municipal water systems often blend hard and soft water to get total hardness in the 40 to 80 mg/liter range.

    At a pH of 7.4 your water is slightly basic so raising the pH is not required. Besides, it would be a bit complicated, such as pumping in a dilute solution of sodium hydroxide (Lye); probably not something that you want to do. The usual "marble chips" won't do anything at that pH.

    Do you have a complete water test? Maybe you could scan and attach it. The paper at the link above describes how to sample the water to test for copper in your water.

    There are a number of chemical additives (mostly phosphates of some form) that are approved for use in potable water. They are usually added at a municipal treatment plant and would be a last resort for household use.

  4. #4


    Date: 12/23/92 REPORT Page 2 of -
    Work Order: 92-12-185
    Invoice #; 60027094
    SAMPLE ID: Spring FRAC.: O1A COLLECTED; 12/08/92 RECEIVED: 12/08/92
    ALkaLinity-Water 66.0 1.0 mgCaCO3/L SM403
    Corrosivity CaLcuLation -1.1 0.10 LangLier SM203
    Tannin and Lignin Water 1.3 0.10 mg/L 1.0 SM513
    TotaL DissoLved SoLids 260 10 nig/L 1.0 12/16/92 SM2098
    pH Water 7.4 0.10 pH Units 12/08/92 SM423
    SAMPLE ID: Spring FRAC.: O1B COLLECTED; 12/08/92 RECEIVED; 12/08/92
    Hardness CaLcuLation Water 100 7.0 mgCaCO3/L SM314A
    HousehoLd - MetaLs EPA200.7
    CaLcium 32 1.0 mg/L 1.0 12/18/92 EPA200.7
    Iron 9.7 0.050 mg/I 1.0 12/18/92 EPA200.7
    Magnesium 6.0 1.0 mg/I 1.0 12/18/92 EPA200.7
    Manganese 0.13 0.030 mg/L 1.0 12/18/92 EPA200.7

    This is the rest of the report. I have had a couple of reports done and can't remember if this is the one from the well I presently use. I should get a new report to be sure the information is accurate.

    My water comes from a 18 foot well in a wet draw located on my property. The only treatment is clorination.

    Thanks for the help.


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