Coffee Break Training: Access and Water Supplies: Fire Flow Formulas: Part 20: National Fire Protection Association 1142, 'Standard on Water Supplies for Suburban and Rural Fire Fighting' [open pdf - 561KB]
"In those areas where water systems are not readily available, and fire-protection water must be retrieved from tanks, ponds, cisterns and other static sources, NFPA [National Fire Protection Association] 1142 provides another method for determining required fire-protection water supplies for buildings. The NFPA 1142 method uses the volumetric capacity of a specific structure to compute the 'minimum water supply (MWS)'. This MWS is a calculation of the total water supply needed; it is not a flow rate."
Coffee Break Training - Fire Protection Series No. FP-2014-3
United States Fire Administration: http://www.usfa.fema.gov/