A few things to keep in mind. A standard whole house water softener uses ion exchange. It takes sodium chloride or potassium chloride and replaces the calcium and magnesium in your water (hardness) with sodium or potassium ions (not salt), as only the calcium and magnesium will cause scale buildup.

If your water is very hard then you are replacing a lot of calcium and magnesium with sodium or potassium. The overall TDS of your water will remain relatively unchanged and is probably too high. Each grain equals about 17 ppm or TDS, so your water is about 425 - 510 TDS. General recommendations for espresso brewing are around 150 TDS.

If I were you I would just purchase an inexpensive TDS meter (less than $20) and check the TDS of your water. Then just mix your softened water with RO water from the store in a proportion to get to around 150 TDS. It should require about 1 part your softened water plus 2 parts RO water.

I had to add a water softener - the analysis came back that ion exchange wasn't going to be as effective as salt. They sold both machines and the salt version was less expensive. Initially I hated the water softener because my taste buds pick up salt too well and I felt like I was drinking sea water, although my wife thought it was perfect.

After reading the manual and some research, consensus said that one should not be tasting salt. I dialed back the machine a point or two, a very minor change. I currently I don't taste any salt - the water tastes great, it's as good as it gets. I travel a bit and I don't taste salt when I've returned from being away; it's not like I've become accustomed to it.

Based on the lack of water residue in the dishwasher (and other appliances), the water softener is definitely working. Prior to installation, we had a massive water spots left behind - the stainless steel walls of the dishwasher were coated white with deposits.

I've done some tuning of the temps/pressures in my machine recently and have had a nice string of god shots, only to say there can be peace between espresso and softened water. I strongly agree on the tds acquisition suggestion - I may pick one up myself at that price.

FWIW the past couple of weeks I've been using Robert Pavlis' recommended potassium bicarbonate/distilled water mix for feeding my Londinium LI and my Ponte Vecchio Export and I'm thrilled with the taste results.

Thanks again Robert!

Mix up a master batch and keep in a container to quickly/easily make a gallon at a time (or 10 gallons as I do): 10% solution of potassium bicarbonate + distilled water (10g potassium bicarbonate into 100ml (100g) distilled water).

Then add 3.8ml/g into each gallon of pure distilled water for your final espresso machine water mixture. You, again per Robert, vary the solution if you find you like it a little stronger or weaker. But for me I'm super happy with adding 19ml/g into each of my 5-gallon containers of distilled.

Solves the hard/soft water wonderment issue along with good taste and per Robert: Never needing to worry about hardness/scale deposits inside the machines.