ive started posting in this thread many times and canceled every time. here is the deal, depending on where you live tap water is probably ok but some areas have a high salinity. some plants do well others dont. i live in one of the higher salinity areas where i couldnt use well water if i wanted but tap causes slight salt burn. in an ideal world you would have perfect everything but thats not going to happen so live with it. on a small scale you can get close to perfect. you can control the water, light, soil etc but it will be at a cost. on a larger scale water management and so forth using commercially available source is what you eat with everyday and frankly america feeds itself and the world with tap water in some of the most productive areas. will your plants do ok on tap, yup. can you do better, yup. is it worth it, up to you.