Comments from Indian govt do not rule out cutting Pakistan's water supply from the Indus:
Analysts like Brahma Chellaney have advocated this approach for pressuring Pakistan:
Others have pointed out that if India does this to Pakistan, then it could set the precedent for China doing the same to India using the rivers flowing out of Tibet which supply the Indus and Brahmaputra.
Personally, I feel that China will never be restrained by India's soft treatment of Pakistan. If and when the Chinese decide to strangle water supplies to India, they won't be constrained by how India treats Pakistan. It would be better for us to use the Indus waters against Pakistan sooner rather than later, in order to neutralize their threat earlier. If China decides to intervene, then it would give us the justification to change our policies towards China and recognition of Tibet.