When you look at a map, it is at once obvious that Cabo is not connected to mainland Mexico, nor even close to much anything else. It is not the same water supply as the rest of Mexico. Also, a major source of water in Cabo is desalinization. The water is generally safe, but there can be occasional concern over the source of delivery.
The water is safe in all of the major hotels and tourist locations. Most of the major hotels have there own desal plants.
Bottled water is readily available.
Casa Vista Hermosa is located in the luxury gated community of Pedregal, and has safe water.