Question

why is right to water incorporatedunder the right to life

Answer 1

Article 21 of the Indian constitution reccognises the Right to Water as a fundamental human right. This section also includes the right to food, the right to clean environment and the right to health that are not possible without right to water.
The very survival becomes difficult in the absence of clean water. Access to basic clean water is every citizens' right and the same has also been recognized by United Nations General Assembly.