Los Angeles County Municipal Code § 507.1 Fire Code

Except as otherwise provided by this section, every application for a building permit shall be accompanied by one of the following:

Evidence indicating to the fire code official that the proposed structure will be provided with a reliable water supply. The fire code official may accept as sufficient evidence a certificate from a water utility that it can supply water to the proposed structure in compliance with Title 20 of the Los Angeles County Code, except that if the fire code official knows that such water utility cannot so supply water, the fire code official may reject such certificate.

A certificate from the Fire Department that there exists, or is under construction, a private water supply which, in the opinion of the fire code official, is adequate for fire protection.

Exception: A certificate is not required for new or existing Group U occupancies with less than 1,000 square feet (93 m 2 ) of aggregate floor area.