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ponents across spatial scales. Urban population growth will put more pressure on existing water resources and will increase competition. In this case, exploring, diversifying, and planning new water supply sources under IUWM will reduce vulnerability and increase security in a scenario of climate change and potential future scarcity due to climate variability. Water Supply Services Water services and infrastructure capacity need to be planned in view of expanding demand due to population growth. IUWM incorporates traditional water supply technologies but also includes innovative approaches to help respond to the challenge of servicing more people. Diversity of water supply, new technologies such as wastewater reuse, and decentralized systems can help accommodate and adapt to growing demands and future challenges in urban areas. However, the current state of infrastructure must first be assessed to estimate future needs. Sanitation Services Lack of basic access to sanitation is a major cause of human disease and contamination of water sources. Dumping of untreated sewage, lack of collection, or poor wastewater treatment infrastructure can affect major surface and groundwater bodies for which cities are dependent on for their water supply. The challenges related to the lack of sanitation and the impact on water resources supply and human health can be dealt with by planning and articulating in a more integrated way the access to basic urban services by the population. The use in IUWM of innovative technologies for wastewater treatment can improve sanitation access and reduce the environmental and social costs of the lack of sanitation among urban populations. Flood Hazards in River Basins Urban populations living in coastal cities are exposed to storm surges and floods. Additionally, coastal cities also face a rise in sea level as well as the impacts of flash floods, storm damage, and coastal erosion. People living in flood-prone areas in cities will be more vulnerable to these challenges, and the infrastructure can suffer severe damages during these types of events. Due to the lack of storm drainage and the nondisposal of solid waste, flood events can increase the risks of sickness through the transmission of water-borne diseases in flooded areas and the contamination of water sources. Floods can also add stress to stormwater and sewerage systems as well as disrupt water supply and treatment systems. By inte-