I have 5 bottles all lined up on my kitchen bench. They total approx. 2.5 litres and I try to make sure I go through them all once in a day. I boil and cool my water which is part of the reason I have so many bottles but also cos smaller bottles kinda trick the mind So I have one 750ml and 4 x 425ml bottles. By far I find it easier to drink the 425ml and can drink half in one go which is how I got to drinking more water each day