Embodiments described herein are directed to methods and systems for treating wastewater or storm water using vermifiltration. The wastewater can come from various sources, such as agricultural sources, municipal and industrial sources, wineries, the dairy industry, and many others. The systems can include vermicomposting beds that are capable of removing high amounts of contaminants, pollutants, and/or toxic substances from wastewater. The wastewater may be applied to vermicomposting beds, for example, by an irrigation system. The irrigation system may provide, for example, improved bed coverage and more even saturation. The vermicomposting beds can remove various harmful substances from the wastewater, such as petroleum products; industrial chemicals; heavy metals (e.g., lead, mercury, cadmium, arsenic); pesticides (e.g., atrazine, chlorpyrifos); and organic compounds (e.g., phenols, polycyclic aromatic hydrocarbons (“PAHs”), polychlorinated biphenyls (“PCBs”)).