I've lived in some countries in Europe where the water is so hard that it is only used for coffee, tea, and cleaning. If people wanted to drink water, they had to buy it in bottles. What I did during those times was washed my hair with a clarifying shampoo (once in a while I used baking soda).

I understand from different articles and the local water department that most American homes have hard water.

Because I usually shampoo with a clarifying shampoo, I wouldn't know if the water was soft or hard. So, after I shampoo, I'm always able to style it.

When I'm in the pool or the ocean during the summer, I follow the same method. I do coat my hair with sunblock lotion before going into the water, though.
Mod CG-Naturally Highly Porous and Dry
This list is not exhaustive...
Winter Regimen
Cowash: various

DT:various
Rinse: Living Proof Curl Detangling Rinse
LI/Detangler: CURLS Cashmere Curls leave-in
Moisturizer: Miss Jessie's Baby Buttermilk
Stylers: various
Sealers: Tamanu oil, OH BSP

*experimenting and loving it!