Question:
I think it is interesting how many of the previously-indie spring water suppliers are now owned by Nestle. I suspect that Nestle has some patents on some pumping and purifying technologies, which gives them a big leg-up in this businessideas?

Answer: While the optimal hardness level for espresso, according to illy and Italian standards is 5GPG, or 9 French degrees, or 90ppm, that level of hardness could be terminal for an American machine that will typically make 85% milk-based drinks. One of the most drastic results is the buildup of minerals around the legs of a commercial heating element. The coating of the element does a number of things, not the least of which decreases thermal efficiency of the element. And the boiler. Continued coating can cause the legs of the element to spread (sorry, ladies) to the point that the element cannot be removed intact for descaling, the sheathing surrounding the coils is compromised, creating travelling voltage to ground, hopefully first blowing the breaker before doing untold damage to the control electronics and the operator. That same encrustation typically affects refill functions where a liquid level probe is employed. The most popular bottled water here in Florida tests out at 15GPG. This is deadly to an espresso machine, commercial or not. My best advice would be to seek out a water that is near 3GPG. Don't use distilled or RO,as it will not make a good coffee, and could affect electronic filling controls.