I have well water it's in the 250 range but the alk is very high off the scale on my test kit. calcium is around 550 PPM. if you let the water evaporate it leaves a white powder
with my RO/DI I get it between 0-4 I found if I warm the water before It enters the RO it's zero and production goes up.
My water had to be tested before I bought house. it's actually very good wayway above standards.