In a large bowl, mix the butter and sugar until just combined.
Add the egg, vanilla and water and mix until combined.
Add baking soda, salt and flour and mic to combine. The dough will be fairly stiff at this time. I find that it's easier to mix by hand at this stage.
Fold in the chocolate chips.
Divide the batter into 18-20 balls (about a golf ball size). Press each ball down to make a 2-inch disk and transfer to a large (15" x 21") baking sheet, leaving about an inch in between. They won't spread out much (see note below) so you can bake them all on one sheet. If using small sheets, you will need to divide them into two batches.
Cook at 350F for 16 minutes. Remove from oven and transfer to a cooling rack.
While these cookie are delicious warm, they taste the best when they are fully cooled down. I think they start tasting the best on the second day.