Posted 2/2/2026 06:36 (#11536633 - in reply to #11535487) Subject: Water makes a difference
Pittsburg, Kansas
Water makes a difference.
Not only in the taste it adds, but also in the extraction of the coffee solids.
We use about 3/4 reverse osmosis to 1/4 tap water to get our desired hardness. We looked up the water test from our rural water district, determined the desired hardness by going down a very deep rabbit hole on coffee brewing water and came up that approximate ratio.
We actually have minerals on the shelf to make water for the espresso machine. But once I found the rural water numbers it is easier to just add back in a little tap water.
Pure reverse osmosis water can actually erode the copper parts in the espresso boilers over time. A person wants a little hardness but not too much. Too much and the boiler will build up with scale. The hardness helps extract more coffee solids from the coffee puck.
Casey's coffee,
