Yeah, with the tap water out here I can SMELL it let alone give it to my plants. (It's disgusting!)

I have the best luck with anything labeled "spring water", BUT - I have a PH pen and after mixing my nutrients with the water, I get the PH to 6.5 using baking soda (to raise) or PH down (to lower).

I found Arrowhead to lock out nutrients without balancing the PH.

I found the local wal-mart gallons of spring water to be perfect during veg, but I still had to balance the PH a tiny bit to make it a perfect 6.5.

I don't use RO water because the process takes everything out of the water, good and bad. A lot of people use it, all you have to do is add a product named calmag plus into the water.

I believe that PH is the key to everything, get a pen if you can - it ran me 40 bucks at the local hydro store.

Hope this helps in any way!