The problem with tap water, even good tap water, is that evaporation and topping off concentrates the materials in the tap water in your tank, the worse the tap water, the faster this happens. Algae is the usual problem at first, but tap water can also contain metals. RO
water starts with 0 ppm
dissolved materials, so the evaporative concentration effect is negligible. For fish only, you can get away with water exchanges and it won't be too bad, but coral is too sensitive for this over the long run. I would get a power head and a good potable water source garden hose. These are usually white in color and are used for human drinking water. Cut off the metal ends and use barbs and hose clamps to connect it. RV stores and hardware stores usually have this inexpensive hose. 100' should be no problem, even upstairs with a strong enough power head or pump.