What is Indus Waters Treaty, which India wants to revise?

Indus Waters Treaty is a water-sharing arrangement between India and Pakistan, negotiated by World Bank in 1960, for water use in Indus River and its tributaries. Under treaty, Pakistan was granted unrestricted use of Indus, Chenab and Jhelum while India was allowed unrestricted use of Ravi, Beas and Sutlej. With this, Pakistan got access to approximately 80% of the water.