Water is so Important while your fasting!
You should be looking to consume around 2 litres of water during your fasting window.
While fasting the main benefits of Autophogy are that your body is burning up dead and insufficient cells in your body. This is obviously a massive health benefit to you but you MUST have enough liquids in your body, in order for your body to remove the dead cells.
Also you will naturally lose a lot of water from the fasting process, so it make sense to keep topping up your body with fresh clean NON Tap water.
If you live in the US, i strongly recommend never drinking tap water, because of the added fluoride in it.