Aruba tap (drinking) water comes from their desalination plant. As of 2007, it was the third largest in the world.
According to WEB Aruba NV
"World Health Organization’s health criteria for TDS (total dissolved solids) is 600 parts per million (ppm). Aruba’s drinking water contains 5 to 15 ppm of Total Dissolved Solids, 40 times better than the criteria for TDS in water supplies. "
You will want ice cubes. Water comes out of the tap warm. Many of the water pipes run above ground due to much of the island being rock.
Packing tip: If you have a mini-fridge in your hotel room, pack a plastic one quart pitcher from home. Being plastic it is light weight and to conserve space you can stuff it with CLEAN socks and tuck right into your suitcase for the trip to Aruba.