S ince May, winter rains have brought a reprieve to the citizens of Cape Town, South Africa. The city had endured severe drought for three years. Concerns that its water supply might run out in the summer have been set aside, hopefully, for another year. But the city remains vulnerable. The situation was very different in 2013. Then, Cape Town had one of its highest annual rainfalls in decades. Reservoirs brimmed, and officials declared there was no need to increase supplies before the 2020s. After another wet winter in 2014, the 6 main reservoirs that feed the city were 97% full. Then the drought began. Reservoir levels fell to 71% in 2015 and to 60% in 2016 (see ‘Cape Town drought’). When they reached 38% in 2017, at the beginning of what looked set to be a long, hot summer, people began to panic. Municipal authorities told residents to slash their water consumption. For suburban households, that meant going from pre-drought usage of around 200 litres per person per day to 50 litres per person per day (picture a bathtub filled to less than 10 centimetres). Although many of their poorer compatriots regularly live with such a supply, suburbanites suddenly had to give up their gardens and collect shower water to flush their toilets. The city more than halved its overall use, to just over 500 million litres a day, and avoided ‘day zero’. Cape Town is one of several cities to see its water supply fail in the past decade. In 2014 and 2015, parts of São Paulo in Brazil received water for only two days a week. Once the city’s reservoirs had been drained of clean water, the utility firm pumped and treated the polluted water that remained. In 2008, Barcelona in Spain had to ship water in from Marseille, France. During its dec- ade-long ‘millennium drought’ in the 2000s, Australia spent billions of dollars on desali- nation plants, most of which have not been used since. It is important to learn from the experi- ences of Cape Town and elsewhere. Urban growth means that many more places will face similar challenges as they compete with surrounding regions for water. Big cities need to begin informed long-range planning and to focus on minimizing risks from cur- rent climate variability. Climate change adds Lessons from Cape Town’s drought Don’t blame climate change. People and poor planning are behind most urban water shortages, argues Mike Muller. The narrow body of water that remained at South Africa’s Theewaterskloof Dam in May 2017. RODGER BOSCH/AFP/GETTY 174 | NATURE | VOL 559 | 12 JULY 2018 COMMENT ©2018SpringerNatureLimited.Allrightsreserved.