I use straight tap water , some times I have to adjust it for example after they changed our hot water tank and resevoir in my building the ph went all stupid.... Lime sure came in handy lol... Now the water is back to ph with no adjustments 'fist pump...
There are fragile strains out there that do hate tap water I would hate to have to invest in a filtration system I can not afford it! So I rely on tough plants that take tap water from germ to flower. I did run in to some strains that did hate the tap water straight up. Dr Atomic strains tend to hate it. Great White North strains tend to hate it but I have had some luck , look at my Lowryders. Mountain bud hated tap water. Strains that I found loved tap water or any sludgy water was Early Wonder Skunk by solar warrior and my Brendas.
We should make a list of strains that are tough or fragile with tap water then sticky it for discussion or to help others 'fist pump