

Yes, all the ways in which human lose water they also lose electrolytes (“salts”). More with sweat, but still some with urine. So, re-hydrating should include at least some of those. This has been known for decades, tho ravers often forget it and have died from hyponatremia.
Tap water has too few electrolytes to restore your electrolytic balance after losing water (via sweating or urination). But yeah, it does technically contain electrolytes.