Click here to Find a Contractor in your area.
In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Need to contact us? Visit

softened water in boilers

PlumdogPlumdog Member Posts: 873
How many issues have others had with softened water in boilers? There is a lot of heresay about this subject, and many differing opinions. And what, really, is the difference. We sometimes check boiler water with a cheap kit that shows PH, relative hardness, chlorine concentration, and such; but I don't trust it, because it always reads close to the same. From what I know, the preferred method of piping softened water is to feed the Water Heater only, leaving raw water for everything else. But some softeners are installed on the whole dwelling (including irrigation!) and we usually recommend seperating all but the hot water side. Our area has all types of water from treated city water to very, very hard well water to very nice well water. We have had problems with scaling in some small-passage type boilers, rusting of steel parts in cast iron boiler systems, and severe rusting in systems with non-barrier tubing and cast iron. And aluminum heat exchangers corroding thru due to incorrect glycol usage. Surely somewhere out there is a body of knowledge for reference that covers the various scenarios!?  


  • Mark EathertonMark Eatherton Member Posts: 5,582
    What I know about softened water.

    It kills living plants, hence the reason they bypass the irrigation system. That and the salt it would consume would be cost prohibitive. It also has a tendency to be hard on the people that use it if they have a propensity towards arterial sclerosis, or hardening of the arteries.

    According to the AMA, these same people shouldn't even shower in the water because they can absorb the salts through their skin.

    As for boilers, steam boilers with continuous make up would prefer the use of presoftened water. Less TDS to have to worry about.

    Conventional water heater manufacturers DISLIKE the use of softened water because it causes their anodes to dissolve.

    Potable water lines also dislike soft water in copper lines, because it doesn't allow a protective patina to be set on the copper from the natural hardness of the water, thereby leaving the copper exposed to other potential threats, like alum deposition and subsequent pin holing. I think the same thing probably goes for closed loop heating systems. They would prefer to see an initial charge of hardened water that would allow a protective patina to be set on the pipes to keep them from seeing too much oxygen.

    Personally, I never liked showering in softened water. It just feels slimy, like the soap never does get rinsed out... but I know some women who ABSOLUTELY must have soft water for their hair.

    Now you know what I know about soft water. :-)

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • meplumbermeplumber Member Posts: 678
    My $.02

    I have heard the same things that Mark listed.

    Also at a manufacturer's class, I remember hearing something about the stainless hx's in mod/cons being unfriendly to softened water.  I will dig around this weekend and see if I can find my notes from that class.

    As a practice, we fill boilers with unsoftened water.
  • Jamie HallJamie Hall Member Posts: 6,659

    it depends!  That's why you can't make up a rule.

    All of Mark's points are right on -- especially showering.  I hate taking showers in softened water.

    The relevant questions are... how hard was the water to begin with?  What was the form of the hardness?  And how was it softened?  And how much of it are you running through your heating system?

    Most times, the hardness was "carbonate" hardness.  Sometimes -- much less often -- it's non-carbonate (usually sulfate) hardness.  And most domestic water softeners (and a not infrequently public water supply softeners) use some form of ion exchange, and the ion exchanged is sodium.  The result is rather dilute sea water, for all practical purposes, and it is corrosive (as well as being an unwelcome source of sodium for those sensitive to it, as Mark points out).  How corrosive depends on how hard it was to begin with (the harder the worse) and how thoroughly it was softened (the more, the worse) and the type of hardness (carbonate is worse than non-carbonate).

    The problem with hard water in heating systems is, of course, scale.  Which forms when the water is heated, driving off some of the carbonate as carbon dioxide, forcing some of the hardness to precipitate as calcium carbonate.  If the water is very hard, and you are using a lot of it (open system), scaling can be quite a problem.  If you aren't using much -- domestic steam heat, hot water heating (closed systems) my personal view would be that the minor scale formation from the initial charge would be preferable to the corrosion from the softened water (in fact, in my part of the world, it is not unusual for our well water to be both quite soft and quite acidic -- chomps through copper in no time -- and the solution is to add hardness: run the water through a system filled with limestone or marble (sometimes dolomite) chips).

    Power boilers or open system boilers are another story; there you do want to reduce the total dissolved solids, again as Mark notes -- but ion exchange softening won't do that; you have to use precipitation softening which is not common in domestic situations.  But hopefully if you are playing with power boilers or open system boilers, you have someone keeping an eye on the overall water chemistry, and doing a lot of fiddling with it (oxygen scavengers, pH adjustment, TDS control, corrosion inhibitors... the lot).

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • HDEHDE Member Posts: 220
    Many fail to understand

    Just so you have your facts straight while you are researching your solution...

    Ion exchange water softening DOES NOT ADD SALT to the water. Ion exchange softening exchanges sodium (or potassium if used instead of NaCl) ions for hardness, iron, and manganese ions that are in the water.

    Sodium (or potassium) is not salt. Neither sodium or potassium creates any of the salt damage you are incorrectly stating in your post.

    No other minerals are exchanged or removed from the water being softened

    The amount of sodium ions exchanged increases as the the amount of hardness, iron, and manganese ions being exchanged increases.

    The benefits of softened water are well proven over decades and decades and decades in the field and are cost effective and reliable.
  • Mark EathertonMark Eatherton Member Posts: 5,582
    Last I checked....

    Salt, which is commonly used in older softeners, use sodium chloride. So, where does the chlorides go?

    Remember, I didn't make up the bit about the AMA warning people who are avoiding salt to stay out of softened water, and to absolutely NOT ingest it.

    As for benefits, I've had to COMPLETELY replace ALL of the hot water mains and circulation return mains in numerous hotels due to softened water. Is THAT considered a benefit that the WQA is not telling us about?

    Just talking out loud.

    As for protection from lime scaling and hard water, look at magnetic and electronic water conditioners. Been around for hundreds of years, and so long as it is not a silica based calcification (a.k.a. glass water) then it will work just fine in keeping things clean, and will actually remove existing lime scale accumulations.

    Soft water has its applications, but in my professional opinion, it is not the residential setting.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • jpjp Member Posts: 1,935
    if you trust Scientific American

    basically the sodium ions go to the shower head.
  • meplumbermeplumber Member Posts: 678
    Sodium is indeed added.

    Sodium in the form of NaCl is added to the post treated water.

    That is why the WQA lists softners as a plausible resolution for low TDS water, along with marble chips, limestone, and dolomite as Jamie said.

    The Scientific American article that jp posted was quoted in a WQA publication a few years ago.  WQA is considered the real expert in water treatment.
  • Jean-David BeyerJean-David Beyer Member Posts: 2,530
    I cannot discuss the effects of using a water softener on plumbing.

    But one thing I do know, having been born in 1938, is that when people used soap flakes to wash clothers, and real soap to wash their bodies and their hair, it tended to result in hard-to-wash-out "curds" that were disagreeable and tended to dull things washed that way.

    Soon after the end of WW-II, soap manufacturers started selling alkyl-aryl-sulfonate detergents for washing clothes, and this greatly reduced the need for water softeners. Then hair shampoo used detergents as well. I do not know what is in bar soap these days. Possibly a lot of people with water softeners do not need them anymore.

    Soap Operas used to be sponsored by manufacturers of soap flakes.
  • GordyGordy Member Posts: 7,106
    edited April 2011
    Ladies, and the softner

     My wife, and daughters can tell exactly when the softener runs out......My hair, My hair.

     So I have what would be pretty hard water 28 grains per public water department information.

     I own a Water Boss which I love because its on demand meaning it regenerates when needed not at a set time whether it needs it or not. 

     According to the article from Scientific American JP posted, and thanks. Each gallon of softened water has 750mg of sodium if the softener is set correctly. So a 10 min shower with a 2.5 gpm head gives you about 18750 mg of sodium IF it were straight hot water. which we know is mixed with cold which only my hot water gets softened. So say half hot half cold still baths you in 9325 mg of sodium.  Question is how much sodium does the body absorb through the skin?  The USDA  Recommended daily intake for sodium is 2400mg for a 2500 calorie diet.....for a healthy person.

     The only thing I could find was a study on bathing in Epsom salts, and how much magnesium is absorbed through the skin. These were baths not showers, but there were definite raised levels of in take through the skin. This was a study to the benefits of bathing in Epsom salts.

    I think this thread got hi jacked, sorry about that, but interesting, and educational findings from post discussions are very contributional in my opinion.


  • PlumdogPlumdog Member Posts: 873
    Softened water in the boiler

    Thanks for the feedback everyone. I agree that softened water feels slimy and won't rinse off, and worry about the effects of salts being absorbed thru the skin and such. And I recall reading that softeners became popular when soaps weren't that great, as one respondant remembers. I see a lot of dated softeners, or equipment that just looks old and bad, and I think these things have quit working properly years ago, and the owners keep pouring sacks of whatever in there just because they always have, and they believe it does some good. I worry when I see big stockpiles of softener "salts" and funky looking white powder growing from the threaded joints and such. There must be a standard test kit for this stuff. I don't mean any harm to the water quality experts that custom design treatments for each special scenario, but I think the "standard" one softener fits all is bogus and probably hazardous.  
  • icesailoricesailor Member Posts: 7,265
    Sodium Chloride:

    Where does the Chlorides go in a water softener? They go out in the back wash. Only the Sodium stays behind in the cation beads. It doesn't leave until an ion of hardness comes by and the exchange takes place. Everything I ever read about water treatment/water softening said that the sodium levels in treated water were very, very low. At least that is what the WQA said when I studied and got certified, back many years ago. Water treatment is a PITA.

    It is deceiving to use the AMA recommendations on salt because they are rather extreme. EPA considers sodium levels over 20 Mg/L as a problem. And some extremist health departments have used this number to create problems in well water. But the EPA level is actually a range from 20 Mg/L to 240 Mg/L. There is 25 Mg/L of sodium in a 8 Oz can of Diet Pepsi. To give an example of how much 20 Mg of Sodium is, take a table salt shaker and try to shake as little salt into the palm of your hand. One shake. That's more than 20 Mg. That's in an 8 Oz serving of Diet Pepsi. I think that cows milk (whole) is 120 Mg or 240. I don't have any to look at.

    High acid or low PH is a bigger problem. Where I work, all domestic water is ground water/well water. It is ALL low PH. It creates incredible problems in heating and domestic hot water systems. If you have water with a low PH, you will have worse copper damage than from "softened" water. "Hard" water usually means that a lot of dissolved solids in the water. It can be calcium, magnesium and iron along with other things. Iron is a form of hardness. A water softener will remove iron that is out of suspension. Ferris or ferric. I can never remember which is which. One is clear, one isn't.

    I really don't think that the amount of sodium left in water after going through a properly maintained and operated water softening treatment system will do much damage. A heating system that has leaks, where it has water added and the water is acidic and has clear iron in suspension will cause far more problems.

    In my acidic Cape Cod water, I have a neutralizing filter. When the filter needs to be replenished, I get green and blue stains in the shower. The soap comes off just fine. In Florida, where they treat the hard water with something, and it still has a lot of hardened in it, it is hard to get all the soap off and to get it to suds.

    My take on water treatment though is that when you have a problem, and you try to treat it, two more pop up. There's nothing like good water.
  • hot rodhot rod Member Posts: 7,014
    as it applies to solar and tankless

    as to steam boilers

    There is a fellow that works for Heatlink that has written a few excellent articles about water treatment for hydronics, I'll keep looking for his archived articles, probably in HPAC mag.

    I know for blending hydronic chemical inhibitors or antifreezes Dow and other recommend Distilled, De-mineralized or RO water be used.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • eluv8eluv8 Member Posts: 174
    edited April 2011
    one other thing

    It was explained to me that a water softener also increases the conductivity of the water thereby increasing the likelihood of electrolysis and the "melting" of the anode rod. I have also seen new 1/4 turn shutoff valves that were installed on homes with water softeners melt the stems away and the handles fall off due to corrosion. My guess is as was explained before the parts are never able to form a protective coating and the anode has to work harder to protect the system.

    I was taught years ago that when installing a water softener on a new home or after major repairs to wait approx 3-6 months  before softening the water as a precaution.

    I am quickly beginning to favor using a whole house filtration system "mountain spring water" and using an electronic descaler to help with the minerals and scale problem. So far the homes I have inspected after using such devices are very favorable. The scale in an electric water heater is not the hard eggshell typically found but more of a mush and in significantly reduced quantities.

    AS for use in a boiler due to the possibility of increased levels of corrosion I have always said no to softened water. If the water was too hard I would truck it in from a more favorable location if at all possible. But this new filtered water system and a descaler I think could be a nice compromise. I have personally seen the results on water heaters and have heard from people I trust that it has worked for them.
  • LanceLance Member Posts: 59

    It is amazing to me how little we learned from our school systems even though we are on a planet largely covered with water, in bodies made up mostly of water. It is good to see learning does not stop when we graduate. Pure H2O is one thing but water in all its variations is another. Even my Master Plumber education is still expanding on the science of water. One thing I did find fascinating is that pinholes in copper piping can be caused by too much velocity. The film that forms on the inside of a clean potable water system actually protects pipe. Flush it away and pin hole city. Did you know water does not always crystallize at 32F. Boy would my science teacher get an F today. I have seen filtered water liquid at 22F at atmospheric pressure, and only when acted upon by adding energy such as heat or movement would it then start to crystallize. The science of water from ice to steam is truly a science that needs much study. One might say water as we call it is actually a solution of many different elements of which we almost never know its true identity and properties without a chemistry lab.
This discussion has been closed.


It looks like you're new here. If you want to get involved, click one of these buttons!