Interesting that you brought this up. I just got around to measuring both my inground fiberglass spa and IG vinyl pool CH last night. The spa was filled with my city water and the pool was filled by trucked in water. Both measured CH=0 and TA was ~125-150.

Not sure if I should add calcium chloride to raise CH or not for the pool equipment since vinyl and fiberglass don't require it. I know for sure my house water is very hard due to lime and I highly suspect the trucked in water is too.