Pre boiled water

Currently breastfeeding and formula, but looking to go full formula once back to work. Baby girl is responding well to Kendamil Infant formula, or at least it seems like it. How much fresh water can I boil in advance, and then portion and put in fridge? I was thinking 2 litres at a time so I don't have to do it every night. The formula is not mixed, just the boiled water.