The Street Vendor Grease Trap is designed with awareness of the problem of clogged fat in public pipes caused by street food vendors pouring waste directly into drains. Although the Public Health Act of 1992 states that food service establishments must separate fat before discharging it into public drains, and fines are imposed for violations, including campaigns to install grease traps, enforcement is ineffective. This is especially true for small establishments like food carts, which often pour wastewater directly into drains because they are mobile and not in fixed locations. Therefore, to effectively manage wastewater, the focus should be on these types of establishments. Everyday Architect Design Studio used data from the research project “Thai Urban Mess Architecture” to develop a solution. We found that popular equipment used to chock up street vendor wheels to increase parking space on footpaths and prevent sliding could be repurposed. Wouldn't it be better to use this insight to develop a new design? The Street Vendor Grease Trap is a portable grease trap that can support street vendors' parking on footpaths and reduce fat grease in public wastewater pipes, addressing both of the city's problems.