The average rainfall in India is about 4,000 billion cubic metres, but most of India's rainfall comes over a 4-month period – June through September. Furthermore, the rain across the very large nation is not uniform, the east and north gets most of the rain, while the west and south get less. India also sees years of excess monsoons and floods, followed by below average or late monsoons with droughts. This geographical and time variance in availability of natural water versus the year round demand for irrigation, drinking and industrial water creates a demand-supply gap, that has been worsening with India's rising population.