Water softener sanitization

[fingerlakes1]

We recently detected a low level of coliform in our home water supply (1 colony per 100 ml according to the lab). We shocked our well, but after testing again, received the same result, which made me wonder if the problem could be our water softener/brine tank--both installed by previous owners, most likely about a decade ago. The system is an Autotrol 255/440 and the brine tank doesn't seem to have a brine well--just the tube running to the bottom. There are also some brownish flecks floating on the water surface in the brine tank, which we think are likely iron. Do you have any suggestions about the best way to clean the system? Thank you!

 

[Reach4]

If you care about the coliform test results, care needs to be taken in sampling. There are variations on suggested sampling techniques, but they have some other things in common:

These describe methods to avoid contaminating the sample.
https://www.doh.wa.gov/Portals/1/Documents/Pubs/331-225.pdf
https://axs-inc.com/wp-content/uploads/2021/10/TotalcoliformInstructionspdf.pdf
https://www.renogov.org/DocumentCenter/View/3801/KSU-Taking-water-samples-MF963
https://servitechlabs.com/Services/Water/WaterSamplingProcedures/tabid/128/Default.aspx

Brown flecks on the water are unlikely to be iron.

With the Autotrol, the air check is in the clear plastic housing up by the valve.

https://terrylove.com/forums/index....izing-extra-attention-to-4-inch-casing.65845/ is my write-up on well and plumbing sanitizing. For sanitizing the brine tank, add 1.2 ounces of water for each cuft of resin into the liquid in the brine tank. Since you have no brine tube, do your best to pour into the liquid instead of the salt. Let it sit for several hours, and maybe overnight. Then do a regen.