Well, I'll have to differ a bit with olympicnut. LA Water is acceptable, but not exceptional. It does not have a bad taste, but it is quite hard. It is not as sweet as New York and certainly could not hold a candle to Hawaii. Almost everybody I knew growing up bought bottled water or had a filter, and many people have water softeners installed in their house. But the real trick is that it depends what neighborhood you're in.

Most urban water in the LA area comes from the Metropolitan Water District of Southern California, which imports water via the Los Angeles Aqueduct (i.e. Owens Valley) and the Colorado River Aqueduct. But local water districts and municipalities also operate wells and reservoirs (even if they are MWD members), and a lot of blending occurs. My hometown (in north Orange County) publishes a map showing three zones where different parts of the city get their water.