Catch the Rain

The places on Earth where insufficient drinking water is a big concern are arid climates, which receive just a fraction of the average $\SI{1}{\meter}$ of rain per year. For example, Dubai, UAE, receives $\SI{100}{\milli\meter}$ $($ or about $4$ inches $)$ of rain per year. It is home to more than five million people. To finish this quiz, let's assess to what extent collecting the little rain that does fall here can help to offset human consumption.

Suppose you design a rain collection system for the roof of a single-family home in Dubai. The roof has an area of $\SI{200}{\meter\squared}.$ If you purify all the water collected for consumption, how many people can the system supply with sufficient drinking water for a year — i.e. $2$ liters each day?

There are $\SI{1000}{\liter}$ in $\SI{1}{\meter\cubed}$ of water.