The giant Cantareira reservoir system, which supplies nine million people, is now only 5 per cent full, and predicted to run dry in April. The smaller Alto Trietê system, which serves three million people in the city, is a little better off, but still only 15 per cent full. With the dry season due, it is calculated that only severe rationing can stop the city's water from running out altogether before the rains start again in November.