San Francisco's much-lauded Hetch Hetchy tap water might have a problematic impurity for some city residents. As SFWeekly reports today, the water that SF Public Utilities Commission loves to brag about gets a healthy dose of UV light and chloramine treatment to bring it up to code before it pours forth from your faucets and fixtures, but the PUC doesn't filter out other impurities and microorganisms that could cause health problems for those with compromised immune systems. From the Weekly's report:

Spreck Rosekrans, an environmentalist and water expert, reports that during San Francisco's process certain microorganisms, such as the protozoans that cause giardia and cryptosporidiosis, are not entirely killed off. The water is perfectly healthy for most of us, but not necessarily for those with HIV, AIDS, or weakened immune systems.

The LGBT Center on Market Street is aware of the issue apparently — David Gonzalez, the center's manager of HIV services, tells the Weekly they've been filtering their water supply in-house since they opened in 2002. The link between waterborne bacteria and infections in those with low white blood cell counts is still being investigated, but at least one other building in town filters their own water supply: City Hall, where the government workers have long been told to bail on bottled water, also filters their drinking water. Although at Civic Center, they're more concerned with that old pipe taste from the ancient copper plumbing than bacterial infections.