If it is pure H2O, there are no micro organisms in it and the container is also non reactant with water and is vacuum packed then it can be stored pure until container is destroyed.
but practically it is not possible because you can't remove every bit of impurities from it. generally packed mineral water bottles have expiry date of 6 to 12 months. i have experience more than a year old drinking water, taste was little changed but it didn't harm. but the case is not the same with every old water.