I know what you mean. Up here in Wisconsin we have rock hard water. In our old apartment I learned to make due. Using more product and spending a little more time working the lather yielded good results. In our new place there is a water softening system. Man what a difference! I use much less product and the lather is richer, slicker, and more cushioning.
Like HoosierTrooper said, distilled water is probably your best bet. A minute or so in the microwave will get it hot but I tried that is it's just not the same as having soft water. Rinsing or softening your beard by wetting your face with water from the tap still seems to affect the lather even though you mixed up your lather with distilled water. It's better than using tap water all the way through, but not the same as using soft water all the way through. I found using distilled water too much of a hassle. Give it a shot and see how it works for you, but you will get good results from your tap water if you use more product.
Hardwater stinks, I know, I feel your pain.
TOFLAC-U, AOM, LEMS/ Stay back! I have a Merkur, and I know how to use it!