Fire Sprinkler Reservoirs - Fire Protection - Underground water tank systems by Darco FIRE SPRINKLER RESERVOIRS are holding tanks used to provide fire protection water for a sprinkler system that demands more water than the domestic water feed line serving the building can supply. Darco manufactures both polyethylene OcTanks and fiberglass underground water tank systems for fire cisterns and fire sprinkler reservoirs. Fire-protection-tanks.com~Site InfoWhoisTrace RouteRBL Check