Abstract: Embodiments of the invention include water treatment systems and components for water treatment systems that possess a collapsed and an expanded configuration, that can be easily transported in the collapsed configuration and expeditiously set up in the field into their expanded configuration. The embodiments include trickle filter/clarifier combinations, upflow anaerobic digester reactors, recirculating anaerobic digesters and their components. In preferred embodiments the volume of the expanded configurations is at least four times the volume of the collapsed configurations.