TRACY (CBS / AP) — A high-tech water-treatment system is making some of Northern California’s cleanest water even cleaner.

The San Francisco Public Utilities Commission on Tuesday unveiled its Tesla Water Treatment Facility, which is the largest of its kind in California and third largest in North America.

The $114 million facility in Tracy uses ultraviolet light to sterilize drinking water and prevent gastro-intestinal illness caused by harmful micro-organisms.

The chemical-free system will benefit the San Francisco water agency’s 2.5 million Bay Area customers who receive their water from the Hetch Hetchy Reservoir.

Hetch Hetchy water is already very clean because of the lack of livestock and people near the reservoir.

The San Francisco Chronicle reports that Los Angeles, Las Vegas and other cities are planning to launch their own ultraviolet treatment facilities.

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