Sodium level in softener discharge

[Bannerman]

Posters periodically ask about potential problems with softeners discharging into septic systems, sump pits, dry wells and the like.

Since the softening process works on an ion exchange principal, I understand the resin needs to be overwhelmed with sodium during regeneration, so as to release the calcium and magnesium (hardness) ions being held by the resin.

While I expect the discharge will continue to contain some level of sodium, it would seem there should be a significantly lower level than contained in the brine as a large portion of sodium would be bound to the resin, with that sodium being slowly released within the softened water consumed in between regeneration cycles.

Are there any studies to indicate the actual amount of sodium discharged during a residential softener regeneration cycle compared to the amount required to regenerate?

 

[DonL]

Are there any studies to indicate the actual amount of sodium discharged during a residential softener regeneration cycle compared to the amount required to regenerate?

Not sure about the Exact answer.

But I would bet that the output is less than the input.

Just a guess on my part.

 

[Sponsor]

 

[Bannerman]

If for example, there was found that 20% of the initial sodium is contained in the discharge during regeneration, there shouldn't be as much concern with discharge as that would be mostly comprised of water, chloride, calcium, and magnesium.

The remaining 80% sodium would then be released during normal soft water use in bathing, cleaning drinking, etc.

My question relates to the actual percentage amount of sodium in the regeneration discharge versus that retained by the softener resin.

 

[ditttohead]

It is easily calculable based on grains vs. pounds... I will try to find my exact numbers on it next week.