Dreads Hair and Scalp Health
Dr. Bronners, like all Castile soaps are terrible in hard water. The minerals in hard water don't break down the soap like it should. While Dr. B's is the best bang for you buck, it just isn't for everyone.
When I've bought Vicki's liquid shampoo, 1 bottle has lasted me about 2 months of washing 2-3 times a week. So the price shouldn't be prohibitive. It's only $10-$15.
As for it making your hair soft, it may feel softer than with Dr. B's or BS, because it's not just stripping the oils away, leaving nothing left. It does mildly condition your hair. Which is a good thing, when the right oils and the right concentrations are used. So your hair will feel softer and lighter. It will still knot well.
Claire, the easiest way to find out is to call you local water dept. I know calling a government agency can be a hassle to get someone on the phone. But it'll be the clearest answer you can get. Colorado, due to the mountains can easily have different water types. The same town can lie on 2+ watersheds, so they actually get their water from different sources. Your county could say one thing on their website, as a general rule. but if you call and give them your address, they can give you the real answer