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Water Quality/water softening


QUESTION: water hardness is increasing after passing thru softner unit although i have recently changed the resin , if we are feeding 50 ppm hardness water then it becomes 100-150 ppm , it is very strange what could be the reason , pl suggest .


ANSWER: What are you using to regenerate the resin?  Normally Sodium Chloride  (NaCl) or salt is used.  However, it sounds to me like a very likely possibility is that you have contaminated regenerant.  It is possible to have some Calcium Chloride or Magnesium Chloride mixed in and this would explain the increase in hardness.


---------- FOLLOW-UP ----------

QUESTION: thanx for answer but we are using Nacl for regeneration .

Hello Praveen,

That wasn't my answer - I'm trying to gather some background information.  We know that you are not making hardness in the softener so the possibilities, in my opinion, are:

1. Contaminated regenerant - perhaps the salt you are using isn't pure.  You may want to have it checked.

2. Bypass leakage -your bypass valve system could be leaking - although this would explain a higher than normal amount of hardness it probably wouldn't explain how it is higher than the incoming level.  It's good to check this anyway.

3. Incomplete rinse - it is possible that you are not rinsing the tank/resin adequately after regeneration.  This is my pick for the most likely cause of  your problem since we have probably ruled out contaminated regenerate.  If the resin is not rinsed and flushed adequately after regeneration there will be an excess of Ca and Mg still in the tank and it will be present in the outflow when the unit is put back on line after regeneration.  This would explain why there is more hardness going out than coming in.

4.  The only other possibility that I can think of is iron contamination.  If iron is being dissolved in the pipes or in the actual tank then some of it may not be absorbed by the resin.  Iron may give a false positive for hardness in some hardness testing procedures.

That is all I can think of.  If you have any questions let me know.  I think your problem is #3 above.  Let me know if you get it figured out.

Good luck,


Environmental Engineer
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Water Quality

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Steve Young


I will answer questions on residential water treatment, i.e. use of softeners, filters, reverse osmosis systems, disinfection, iron and/or sediment removal and other issues facing the homeowner. I have worked extensively with well water systems.


I have worked in the water treatment area for many years as a consultant and as a professional environmental engineer in the private industry sector. I have designed reverse osmosis, deionization, and water softening systems. I have also done work in water quality and stream and river remediation as it relates to the Clean Water Act.

I am currently serving as an Expert for Home Improvement, Travel (New Mexico) and Travel (North Carolina);

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