how much rain do we have anyway?

We have one of the rainiest countries in the world, even in the arid part where delhi lies, it rains just over 2 feet a year. The catch is that it comes all at one time of the year. But if we stored this water, is there enough? A simple calculation taking the area of the city and dividing by the number of people will give us the area per person. With 1483 sq km and a population of around 15 million. We get almost 100 sqm per person. At the annual rainfall this gives us 65,000l per person per year. at the dub norms of 135lpd the amount required is 49,275l . . so we're in the green with quite a margin.