Phnom Penh’s sanitation system is a combination of the drainage system and sewage system. Storm water, household wastewater, and industrial wastewater all flow together out of the city to the detriment of the natural environment and the humans that depend on it. This continued persistence of an inefficient and harmful system is explored using path dependency theory. Path dependency constrains the system to linear development and reflects the historical context in which decisions were made. Phnom Penh’s sanitation system is used to exemplify components of path dependence and their effect on implementing change.

To incorporate room for change into Phnom Penh’s sanitation system, the inherent longevity in built infrastructure must be overcome. Building infrastructure is expensive and the learning and coordination that is associated with it is not easily replaced. The social context is ultimately responsible for the investments made and the type of system expressed. Phnom Penh’s sanitation system reflects a historical legacy of colonial rule, decades of war, political chaos, and an influx of international aid contributing to an inefficient system being developed. The presence of unpredictability and inflexibility in the system can result in an inefficient system being sustained.