How Soft Is Too Soft?

The Tank How Soft Is Too Soft?

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    I apologize in advance for a slightly off-subject topic….although some relevance may gain me some redemption.

    I do have your water heater hand-book, and there is some mention of overly soft water using up anodes faster than normal. Are there any other plumbing or hardware concerns with water softened to 0 ppm?

    The reason for the question, I have installed a new reverse osmosis system, and the mfg’r is recommending water hardness of 0 coming out of the softener. Currently, it tested 5 ppm. It’s well water, 50 ppm prior to softening.

    So, if it’s only the anodes that don’t like the soft water, I will just check/replace them more often. (Just installed a new AOSmith with dual mag. anodes) I just want to make sure the rest of the plumbing won’t form a mutiny.


    Randy Schuyler

    The rest of the plumbing is, in fact, the other concern. You may start getting pinhole leaks.

    Actually, we recommend leaving from 50 to 120 ppm of hardness. If you already had only 50, I can’t help but wondering why the softener, although well water is usually a lot harder than that and the reason people soften it.

    Randy Schuyler


    I found this, on, by Joseph Harrison.

    Your thoughts and comments….

    (Not trying to be adversarial, just trying to understand what I’m doing, and why I’m doing it…)

    Softened Water Does Not Cause Corrosion

    From Volume 20, Issue 7 – July 1997

    Decades ago, a misconception developed that leaks in early-generation water softener tanks were due to soft water not to poor corrosion-resistant coatings and postwar production shortcuts.

    The rumors grew into accepted “opinion” when a research analyst failing to note that softened water differs significantly from low total dissolved solids (TDS) naturally soft water published statements linking softened water to corrosion. This belief reached damaging proportions for the industry when so-called corrosive softened water was noted as a lead-leaching risk in U.S. Environmental Protection Agency (EPA) and American Water Works Association (AWWA) publications during the 1980s. Soon, similar concerns about potential copper and zinc leaching began to arise.
    These misconceptions can now be laid to rest with the completion of a Softened Water Corrosion study by the EPA and the Water Quality Association (WQA). The study concluded that there is no significant difference between softened water and its source water. In fact, there were indications that in some cases softened water may be less corrosive.
    The WQA’s position for many years has been that the removal of hardness from water using an ion exchange softener does not affect the factors that cause or accelerate water’s corrosivity.
    In 1993, the EPA and AWWA corrected their respective brochures Lead in Your Drinking Water and Lead Free, What You Should Know About Lead to clarify that dissolved oxygen, low pH and naturally soft water with a low mineral content, but not softened water, are common causes of corrosion.
    The WQA and the Water Quality Research Council (WQRC) determined, however, that this issue could ultimately be settled with a study by the EPA. The WQRC provided $50,000 toward a cooperative research and development agreement between the WQA and EPA’s Risk Reduction Engineering Laboratory to determine if domestic softeners increase corrosion by-products in household plumbing systems.
    Thomas J. Sorg and Michael R. Schock of the EPA’s Drinking Water Research Division became project manager and principal investigator, respectively, on a pilot plant study on two test waters. Phase One studied at the city of Cincinnati’s Bolton Water Treatment Plant with 7.2 grains per gallon (gpg) total hardness and 9.1 pH; Phase Two was at the Indian Hill ground water supply near Cincinnati, OH, with 18 gpg total hardness and 7.3 pH.
    The two test waters each fed two test systems one containing an ion exchange softener and pipe loop system and a second containing only a pipe loop system. Both phases tested the effects of softened water (to less than 1 gpg) and non-softened water in pipe loops of lead pipe, copper tubing, galvanized pipe, copper pipe with 50/50 lead-tin solder joints and brass faucets. Each phase was run for 470 days, and the water was periodically tested for lead, copper and in Phase One zinc leaching.
    The testing was completed on March 12, 1996, and data was compiled into a preliminary summary report presented by Sorg at the WQA Convention in March 1997. The results will also be published in an official EPA research report.
    Study Results Support WQA Position

    The study’s introductory literature review points out that calcium is not a major factor that influences the rate of corrosion. The report states:
    “Unfortunately, calcium carbonate saturation indices have been used as a surrogate measure for ‘corrosivity.’ By erroneously using these indices as a surrogate measure for ‘corrosivity,’ much information has been generated in the past. High pH and high alkalinity also produce higher (less corrosive) values for the CaCO3 saturation state. However, that combination has been demonstrated theoretically, by controlled experiments and by field data to be detrimental in some substances to either lead or copper solubility.
    “The AWWARF Lead Control Strategies Manual states: ‘In spite of the fact that there is little evidence in the research literature that adherent, continuous CaCO3 films actually form to seal lead pipe from leaching, calcium carbonate deposition has gained wide acceptance as a viable lead control strategy.’ The manual further states that the water quality factors that have the greatest influence on lead mobilization are pH, alkalinity and dissolved inorganic carbon (DIC). The treatment strategies stressed, therefore, are pH, alkalinity and DIC adjustment and the use of corrosion inhibitors such as orthophosphate and silicate compounds. The addition of calcium is not considered a corrosion control treatment strategy. It can be reasoned, therefore, that the removal of calcium may not necessarily increase the corrosivity of water.”

    The EPA/WQRC study results support this hypothesis. The following are the study’s conclusions:
    SYMBOL 183 f “Symbol” s 13.5 Considering all the lead-, copper- and zinc-leaching data from all loops and faucets from both phase one and two, there is no clear evidence of a pattern that ion exchanged-softened waters produce higher metal levels than the non-softened water. The water quality data shows little difference between the non-softened and softened water qualities for either alkalinity or DIC, two significant corrosion factors.
    SYMBOL 183 f “Symbol” s 13.5 The ion exchange softening process increased the pH of the control waters by 0.2 to 0.3 units, which could have a beneficial effect on the metal level. Consequently, except for the decrease in calcium levels, the softened water did not change any of the significant water quality corrosion parameters that would cause a prediction of higher leaching of metals in the softened water system.
    Although these studies involved two water qualities both considered to be non-aggressive the results cannot be extrapolated to all water qualities. However, these results do indicate that ion exchanged-softened water will not necessarily produce higher levels of metals.
    The following are some specific findings of the study:
    SYMBOL 183 f “Symbol” s 13.5 The only data observed to have a consistent difference in metals levels throughout the Phase One study was the lead levels from the lead pipe loops. In this case, the levels of the non-softened (hard) water loops were always 0.2 to 0.3 milligrams per liter (mg/L) higher than the softened levels, which is contrary to the hypothesis that softened water is more corrosive than non-softened water.
    SYMBOL 183 f “Symbol” s 13.5 The lead levels observed in Phase One (softened and non-softened waters) for lead pipe were much higher (by a factor of approximately three) than would be expected for a water of the same pH and DIC. Some pipe surface reaction not directly resulting from hydroxide or carbonate ions may have occurred.
    SYMBOL 183 f “Symbol” s 13.5 The lead levels from the faucets in Phase One were slightly higher in the softened water system, but the absolute levels were very low, suggesting little or no difference.
    SYMBOL 183 f “Symbol” s 13.5 During the last six months of the Phase One study, the copper levels of the copper tubing loops were about 0.01 to 0.02 mg/L higher in the softened water loops, while there was no difference between the copper levels of the copper pipes or faucets of the softened and non-softened systems.
    SYMBOL 183 f “Symbol” s 13.5 The general outcome of Phase Two was very similar to that of Phase One. Little difference in metal levels was found between the control and test systems; where differences were apparent, there was no pattern to the softened water metals being higher than the nonsoftened water metals levels. The only data showing a consistent difference in metals levels was the same as in Phase One, where the lead levels from non-softened water loops were about 0.2 to 0.3 mg/L higher than the softened water loop levels.
    SYMBOL 183 f “Symbol” s 13.5 The copper leaching levels from the soft copper tubing, copper solder pipes and faucets all showed extreme variability and a high dependency on the oxygen content of the water. Copper levels were increased in direct relation to the higher levels of dissolved oxygen in the water. Dissolved oxygen was found to have such a great influence on the copper levels that any potential impact of hardness, in comparison, could not be detected.
    Joseph Harrison is technical director of the Water Quality Association (WQA), Lisle, IL. The WQA and the Water Quality Research Council (WQRC) thank the U.S. Environmental Protection Agency, and in particular Thomas J. Sorg and Michael R. Schock, for their efforts with this study. WQA also thanks the members of its Science Advisory Committee and WQRC Board of Directors for their support, involvement and direction throughout the study’s development and progress.

    Larry Weingarten

    Hello: I’m not dissing the Water Quality Association, but that organization is made up of folks who soften water. I’ve seen their science slant in favor of softening 😕 That’s just my opinion. Please check it out for yourself and form your own opinion. I’ve been in the plumbing field for nearly thirty years and have had many opportunities to see how water quality and water teatment affect things. My observations line up with what the National Association of Corrosion Engineers has found… Their suggestion; Leave 60 to 120 ppm of dissolved solids in the water after softening. That’s roughly 3 to 6 grains. Over softened water DOES attack copper piping as it strips off the protective calcium coating that many waters naturally put there. This allows the pipe to corrode, showing up as elevated copper levels in the water and also as blue staining. Over softening can completely eat up the anode in your heater in six months 😯 I’ve seen it in the field and in print.

    So, do what you are comfortable doing 😎 Ima stickin’ to my guns.

    Yours, Larry


    This is precisely why I value your direction….years of experience. I’m trying feverishly to dig up everything I can find on the subject, pro and con. I will look deeper into the WQA. So many special interest groups, it’s hard to know who’s in who’s pockets these days…:? They certainly have a wholesome name!

    I suppose a R/O bladder every few years is cheaper than new plumbing.:shock:

    I will keep researching (because I’m strange that way…), but I do tend to favor you guys at this point. After all, my new water heater with all your gizmos rocks!;) (I honestly considered a glass door to the water heater closet, it’s THAT pretty…)

    Larry Weingarten

    Hmmm: A glass door for water heater viewing and admiration is something I’ve never considered before. You may be onto something :dude:

    Yours, Larry


    I just realized my previous data was incorrect. My water analysis was in grains, not ppm. This probably now makes more sense: Hardness before softening; 50 grains, after softening; 5 grains. If my math is close, this would equate to about 1000/100 ppm respectively.

    So, by your (& NACE) standards, my current softener setting is in the “preferred” range.

    I’m feeling better about things, but I still want to do more investigation. For now though, I may dial in just a touch more salt, to get closer to the 3 grain reading.

    Sorry for blathering on and on…. Hopefully others are finding this discussion useful/interesting/entertaining, etc…:?

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