Collected rain or air conditioner condensate has rather low ppm/salts, and may be an option as the water source.
Yes that looks like a ton of calcium carbonate. You could spend some money to get a water test from the water out of your tap or just buy a small RO unit to make water for your garden and maybe drinking water for your household?
Yes, blend your water 2 gal of DI to one gallon of tap and even if your EC pen is correct this should bring it into acceptable levels.I’m looking at undersink R/O now, but until I can move forward with that can I use distilled water?
I’m assuming that would have created issues for my soil-based plant outside that never really did much?