I have very hard water too but have a water softener. Hard water can make building a lather very challenging and some soaps flat out won't work. But that would be an easy test. If you have no problems with the bottled water then you have solved the problem. If you still have problems then we have to look at your technique. Really, technique in lather building involves the amount of water in your brush and the amount of time you go about building it. Even the smallest and cheapest brushes can build a good lather it's just with larger and better ones it just comes more easily.

When I use MWF for instance I keep my brush pretty wet because that soap requires more water than most others and I just go round and round with my brush with a little pressure and in about 30 sec I have enough lather to shave a platoon.