We visit and just bought a second home in a city in WV (for us, it's really rural.) Although we have public water and sewer, there is a water softener. We haven't spent a lot of time there, but I find that my hair is less curly when I'm using softened water.
You may want to up your level of "cleansing." You could use some of the cleansing conditioners that contains a mild surfactant like Cocamidopropyl Betaine. I find that the cleansing conditioners that don't have a mild surfactant don't do much. At home, our water is on the hard side. I use CJ Daily Fix every few weeks. I can't use it too much or it's drying for my. DevaCurl NoPoo also contains the coco b, I find that drying with any use.
My new love is Curly Kinks Natural Shampoo
The coco b is further down the ingredient list. My hair feels great after I use it. The funny thing about the Twirly Curl Cleanse is that it's called a cleanse in the name, but the website also refers to it as a shampoo. I think that's because of the coco b--if it has a surfactant, is it really a lowpoo and not a cleansing conditioner. For me, it's the ingredients and not the name. People can name a product whatever they want. It's how it performs.
If the salts from the softener continue to bother your hair, you could do a final rinse with distilled water???
3a (Corkicelli), highlighted, fine, low porosity
modified CG, since April '07
CG since 3/11/08
HGs: Curly Kinks Satin Roots, Curlycue ReNew and Coil Jam; homemade FSG and okra gel; soap bars; DM MiraCurls Curling Gelly; UFD Curly Magic; Shescentit LIs; Sevi conditioners; Botanical Spirits Puree, CJ Repair Me