hFirst off, it's soil less, it may look like dirt, but it is not. I provide via fertilizer everything that plant needs in the medium. My style is closer to hydro than soil.
Soil less actually gives more control, not less. I run multiple strains at once. Some strains are heavier feeders than others, I can individualize a feeding schedule for each plant.
When it comes to drainage, it's trial and error. I found happy frog at a 60/40 split with perlite works perfect for me. Quick drainage, great air exchange, and I can easily know when and how much water to provide.
most people have quality water in the United states. Unless you are using a well, most city water is perfectly fine to use. Get a water quality test done if you hand doubts. I find many people find something to blame when another variable (usualy their own mistakes, shit just look at some of these posts for help). That's not to say some people's water is fucked up. I just know local growers who blame their water when they should be blaming the massive fertilizer dump with the constant additives. So instesd of learning, they waste money in RO water. Some people...