Tuesday, November 3, 2015

Water Softener Backflush Discharge Issues


Mrs. M  is my wife, whom you spoke with last month.

We have questions regarding water softener backflush discharge into the septic. I have heard this creates issues with the biodegradability of the sludge tank. Can you please comment on that.

Is it common practice to run this discharge outdoors to daylight?

How effective would a reverse osmosis system (with prefiltration of iron prior to RO) be for a small household?


Hello Mr. & Mrs. M,

Thank you for getting back to me, happy to help here.  In regard to the discharge it is true that if a Softener was to backwash with exorbitant amounts of salts and was to do so frequently that would indeed ruin a septic tank. 

This is how Softeners were used way back when however now we’re using a limited amount of salt (6 – 8 lbs. per cu. Ft.) rather than 25+ per cu. Ft. and they are mandated to backwash based upon gallons used instead of by days.  This process is completely safe for septic systems and actually helps in the cleaning during a regeneration cycle.

I wouldn’t recommend discharging to the ground, not recommended as the salts expelled in the regeneration cycle will still destroy plants over time, no matter how much we use to regenerate.  Simply run to septic and you are good to go.

For your RO question I am assuming you are referring to under the sink in the kitchen?  If so an RO would work great in dropping the TDS level down as well as removing any salts that are added during the cation exchange softening process.  It is very common practice to use an RO with a Softener for drinking water, cooking, coffee, tea, etc.   Here’s a link to an RO I’d recommend in your case:

USA High-Flow 4-Stage 60 GPD RO System

USA High-Flow 4-Stage 60 GPD RO System
  • 60 Gallons Per Day (GPD) Thin Film Composite Membrane
  • Includes faucet, tank, and tubing
  • NSF Certified Quick-Connect Fittings
  • NSF Certified Metal Bladder Tank
  • NSF Certified 10 Micron Carbon Block

Comes complete with easy-to-follow installation instructions.
If you want more detailed information about this product, you can check out this link.

You can also check out this diagram to have a quick view on how this works.

RO system

All in all your water test results were in pretty good shape really with minimal over the limit for Iron, the TDS was still good, and the hardness isn’t really all that high.  A Water Softener implemented would do a great job in your case, no question about it.  Not to mention this system is quite maintenance free, with having to add 4 – 5 bags of salt to the salt tank about once per year.