Yes, tap will have nutrients. But, may have too much. Do you have a ppm meter? (If not, HM EZ-TDS for $20 on Amazon. You can calibrate it with 1g table salt in 1L distilled water, producing 1000ppm). That would tell you if your tap is safe. It's a problem if it's too high. Mine is 600-800. I dilute it with RO filtered water (dispensing machines) to get 150ppm (0.3 EC). If you're using AK Fish, you could get AK Kelp which has minerals. But, a balanced ferilizer would be better. Use those AK products as supplements. (I use Grow More Sea Grow. It's not entirely synthetic. I like that and supplement with organic goodies. It's cheap. $1 per plant, per grow. A lot of people use Jacks Classic. Similar expense.).
High ph water (like you mention) won't help. Pure water has no buffering and will be pulled to the soil's ph much more than the soil will be pulled to the water. I don't ph my nutrients. But, I do add 1-1.5 Tbsp Hy-Yield Agricultural Lime (dolomite) to 1 gal of soil. That may be crucial to not ph'ing, I don't know.
It's not bad right now. I would let it dry out. What you risk is trying to fix it by pouring more water in. Find out about your water. If you're in the US, your city/provider is required to publish an annual water quality report. You can google for it. Otherwise call them for info.
I would let it dry, and think about what you're going to do for nutrients.