I water with tap water with no issues whatsoever. We have chlorine and chloramines, at about 200ppm, 7.5pH, typically. I cycle my nute solution 24 hours before feeding, which probably handles the chlorine. The chloramines seem to have no negative effect on my plants.
I seriously recommend a foliar of grow nutes.
I doubt Cal or Mag are an issue at this point, but once you get to flower you may have issues without a supplement if you keep using distilled. The demand isn't high for those right now, and the supply in the soil should be sufficient. It also looks like neither. It looks exactly like an N deficiency.
Nitrogen foliar feed...at least to factor deficiency out. If you're growing organic with good nutes and soil, pH almost certainly isn't the issue.
It could also be overwatering, which is looking like a good runner up for your problem. Which is why I recommend a foliar feeding. Let that soil dry out a bit.