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Common Water Myths

Sals Plumbing wants to educate people on water quality and safety. We took this excerpt from the Water Quality Association website. This is very information and educational.

 

“Is softened water more corrosive?No.
Because the Langlier (calcium saturation) Index is lowered in      water that has had calcium removed, skeptics sometimes consider softened water to be more      corrosive. But softening of water via cation exchange does not make water more corrosive. In fact, the U.S. Environmental Protection Agency (USEPA) and the American Water Works      Association have both recently corrected their enclosed brochures as to the misconception      that ion exchange softening has an effect on the corrosivity of water.

WQA has recently completed a research study with Tom Sorg and      Mike Schock in the USEPA Drinking Water Research Division in Cincinnati, Ohio to clarify      the noncorrosive effect of the ion exchange softening process. The study is on well waters      with 23 and 11 grains per gallon (gpg) total hardness and softening to less than one gpg      to examine any differences between the hard and softened waters in corrosion rates and      leaching from lead, copper, copper tubing with 50/50 solder, galvanized pipe, and brass.      Results from the study shown no increased dissolution of lead in the softened water. The      final research report is now available from the WQA Publications Department, and states      the same conclusion—that ion exchange softened water does not produce higher metal      levels than nonsoftened water.  Research results, such as these, confirm the minimal      effects of hardness minerals on corrosion.

WQA also has available other materials to show that ion      exchange softening does not affect any of  the factors which contribute to water      corrosivity. Neither the water pH, dissolved oxygen content, TDS concentration, electrical      conductivity, ammonia, chloride, or sulfide amounts, temperature, nor flow velocity are      significantly altered by home water softening. While it is true that soft water will      deposit less scale coating on metal surfaces, the softening itself will not change a      water’s corrosivity or lack of it. Corrosion of copper pipe, for example, is most often      caused by oxygen concentrations in the water. Oxygen corrosion is usually found with      surface water supplies and in deep well supplies in arid regions.

Municipal water systems often use calcium carbonate      saturation indices to help control precipitation in city water mains. This information is      useful where utilities try to lay down a protective film in hopes of retarding the rate of      corrosion in municipal distribution systems. The Langlier Index (LI) is such a calcium      carbonate saturation index that measures the potential of a water to deposit calcium      carbonate scale. Water with an LI greater than zero tends to be of higher hardness and      alkalinity and therefore to be scale forming. An LI less than zero represents water that      tends to dissolve CaCO3.

However, these calcium carbonate saturation indices do not      rate the corrosive tendency of the water itself, nor the effect of scale in household      plumbing. While some scales are capable of such protection, scales in a household water      system are often porus or soft and thus non-protective. It is rare that hardness scale      formation is uniform in household plumbing, for the heaviest scale usually forms at points      of greatest heat transfer and at low points in a system. In a water heater, for example,      most scale forms at the bottom where heat is applied, while the top of the heater tank may      show little or no scale. Thus, even in hard scale-forming water, thousands of water      heaters can show that corrosion has occurred under or through the scale, or in locations      where protective scale has not formed. Thus, it is clear that corrosion protection in      household plumbing is not assured simply because a water heater will precipitate calcium      carbonate, as indicated by various scale indices. Further, none of these indexing methods      take into account the effects of dissolved oxygen, ammonia, chlorides, hydrogen sulfide      and other sulfur compounds, water flow velocities, the presence or absence of solid      particles or the volume of water through the system which markedly affect water      corrosivity.

The simple replacement of hard water calcium and magnesium with soft water sodium or potassium has no detrimental effect on water contacting materials. In fact, the nonscaling characteristic of soft      water is a benefit to such pumping and plumbing appurtenances. Ion exchange      water softening neither causes nor controls corrosion. Please call the Water Quality      Association if you have any questions or would like to discuss any of these materials.”

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