That depends on the comfort level you want and the surroundings.
Under normal circumstances, you need 1.5 to 2 litres of water every day. Part of this will come with your food or beverages. In a dry hot climate you will lose more water through perspiration, so you will need more, up to 9 litres a day (but there are ways to avoid water loss, like staying in the shade).
Water for cooking
Most foods need at least a bit of water to be cooked in (or steamed). If you don't throw away the water, but use it for a soup, you can add that to your drinking water.
Those were the essentials, without which you cannot survive in the long term.
Then, of course, there is "luxury" water:
- Flushing your toilet
- Washing your car
- Etc, etc
Water use in the UK is about 150 litres per person per day!