my water table i built with brute trash cans...they work great. You will have at least 2 to 1 waste to good water so use that "bad water" for something good like water the lawn or laundery...will save on your water bill alot.
I was in Ocean Treasures the other day, and a reef keeper was there having his water tested. He told me he has always used tap water (SF tap water). His various nitrogen levels were all zero. Not sure if they tested phosphate. I was floored.
I use water straight from the tap and use some Prime to dechlorinate it (dechloramine it). My SPS are off the hook with growth and color and everything is doing great. I have a good refugium though and my chaeto grows pretty fast so that may be why I'm getting away with it.