1402.1 Sizing.
PC § 1402.1
The system shall be sized in accordance with the sum of the output of all water sources connected to the subsurface irrigation system. Where gray water collection piping is connected to subsurface landscape irrigation systems, gray water output shall be calculated according to the gallons-per-day-per-occupant number based on the type of fixtures connected. The gray water discharge shall be calculated by the following equation: C = A × B (Equation 14-1) where: A = Number of occupants: Residential – Number of occupants shall be determined by the actual number of occupants, but not less than two occupants for one bedroom and one occupant for each additional bedroom. Commercial – Number of occupants shall be determined by the New York City Building Code. B = Estimated flow demands for each occupant*: Residential – 25 gallons per day (94.6 lpd) per occupant for showers, bathtubs and lavatories and 15 gallons per day (56.7 lpd) per occupant for clothes washers or laundry trays. Commercial – Based on type of fixture or water use records minus the discharge of fixtures other than those discharging gray water. * Alternative estimated flow demands for each occupant shall be permitted based on actual calculated water usage for the building. C = Estimated gray water discharge based on the total number of occupants.
