A filter module for filtering fuel in an engine system includes a primary filter, a secondary filter, and a module housing. A drain valve is movable between a closed position blocking a drain port in the module housing, and an open position. A service valve assembly is positioned at least partially within a cross passage in the module housing and adjustable from a closed configuration blocking a primary-side fuel passage from a secondary-side fuel passage in the module housing, to an open configuration, to drain fluids from the filter module by way of the single drain port.