Water, water nowhere

Have you ever worried if water will come out of your faucet? While running out of water may seem far off to some, Cape Town, South Africa is already experiencing a dramatic water crisis. This spring, the city came dangerously close to Day Zero. On this day, pipes would have shut off due to the cities ultra-low water levels. Instead of running water, 3.75 million city residents would have been allocated 6.5 gallons per day. Some people in the city already live without proper water access, and this water crisis is highlighting socio-economic disparities in the city. Wealthy city residents are taking matters into their own hands by drilling wells. Luckily, extreme water conservation measures, a giant public education campaign, and timely rainfall helped defer Day Zero. Cape Town’s struggle to supply water to their citizens should be a message of warning to the rest of the world.

Human movement from rural areas to urban centers creates new challenges for city governments. Housing, natural disaster mitigation, and waste disposal are just a few city functions that will need innovation and growth as city populations strain communal resources. Water poses unique challenge for cities. A city’s water supply does not easily scale with population growth. Water is a regional resource and most cities rely on complex urban water infrastructures, including inter-basin transfers, for safe and reliable drinking water.

A new study published in Nature analyzed current and future water availability in 482 of the world’s largest cities. To understand how water needs will change in the future, the researchers looked at regulatory and physical factors that limit water resources. Water laws determine who has the rights to water when there is a limited supply – agricultural users or municipalities. For physical characteristics, they analyzed water scarcity, rainfall predictions, population growth scenarios, agricultural need for water, as well as the amount of water necessary to leave in the rivers and streams to preserve ecosystem function. Researchers found that when environmental water needs are considered, 46.6% of cities will face a water deficit by 2050. The study identified that the major point of tension will be between agricultural water use and city water use.

Armed with this knowledge, we can act preemptively to prevent conflict and decrease water needs both in cities and in agricultural areas. In addition to encouraging water saving in farming, cities must also reduce their water use. Efficient utilities systems, the use of gray water, desalinization and rainfall capture can go a long way to helping cities meet water reduction goals. To extend the life of their water system, Cape Town is cutting consumption and investing in desalinization plants. Other cities must follow their lead. This article highlights the importance of mutual progress by cities and agricultural water users towards a sustainable future.