The present application is directed to a manifold system for low pressure and high pressure fluids. The manifold system may include one or more manifold sub-assemblies that may be assembled together, separated apart and replaced as desired. In oil and gas hydraulic fracturing operations, each manifold sub-assembly includes two or more low pressure fluid lines and two or more high pressure fluid lines for fluidly communicating with hydraulic fracturing pumps. High pressure fluid may exit the manifold system via a single line or multiple lines.