Waste collection services often do not reach all residents and landfills remain the preferred treatment method. Many Southeast Asian cities have also experienced increasing water demand and situations of water stress and scarcity, aggravated by the poor coverage and quality of water supply infrastructure. Water sanitation infrastructure is also sub-optimal and has not kept up with the pace of urbanisation, and the quality of water streams and bodies is often under established quality standards. In many Southeast Asia cities, informal services and infrastructure have compensated for the absence of formal structures.