The financial viability of multistage membrane technology for landfill leachate treatment compared offsite and onsite scenarios for PFAS compliance. Both the onsite and offsite scenarios in the study include pretreatment processes before membrane treatment and excluded the final fate of PFAS. The primary cost driver for onsite treatment is operational expenses (45%) due to high electricity and chemical usage, while leachate transportation accounts for 95% of offsite costs. Using 1 g of PFAS treated as the functional unit, the onsite scenario's life cycle cost is 83% lower than the offsite scenario. However, treating 1 m³ of raw leachate costs $1.96 onsite compared to $2.50 offsite, reflecting a 21% cost reduction for onsite treatment despite its higher initial costs. The net present values of a two-pass spiral-wound reverse osmosis system for additional leachate treatment in Thailand were $577.9 million USD for a system with an evaporation pond and $391.9 million USD for a system without one.