I went to a conference in Berkeley. I couldn’t drink their tap water. Even the Coke (coming from the machine, not bottle or can) tasted bad because they had to use the tap water.
San Francisco actually has always had very good water because it comes from the Sierra Nevada via Hetch Hetchy Reservoir. IIRC, the system has changed, and it may not come from Hetch Hetchy, but it still comes from the mountains.
New York City also had great water, because it came from the Adirondacks.
So some cities do have really good water. If buying bottled water from elsewhere was just a status thing, he was right to cancel that expense. People can fill their water bottles at the office fountain or cooler, if the water’s good. If it’s bad, however, he should be reasonable and have the city procurement offices look for the cheapest source for bottled water. Or people can bring their own.