San Diego County Municipal Code § 2808.7 County Fire Code

The operator shall provide and maintain approved fire hydrants and waterline mains as required by the fire code official. Water lines may be approved aboveground lines supplied from a reliable water supply with adequate protection against impact and fire flow reaction. Hydrant spacing shall be at 400-foot intervals along primary fire access roadways. Fire flow at each hydrant shall be least 1000 gallons per minute at 20 psi. Duration of the required fireflow shall be as determined by the fire code official.

Above-ground water storage tanks may be installed when authorized by the fire code official where public water supply is not adequate to meet fire flow requirements. Volume and duration of the required fireflow shall be as determined by the fire code official.