…because the shape of the water bottle isn’t uniform either. Part of my new year’s resolution is to drink 4 liters of water per day, so I spend a lot of time looking at those lines. Edit: 4 liters is a lot, but appropriate for my size and activity level. Without conscious consideration I don’t drink enough water. It looks blue because the bottle is blue.
It is on the upper limit but OP could just be huge. Like GoT-Mountain-huge, if you’ve seen the series. Then 4 liters is maybe ok.
I’m 5’11, 170lbs and drink about 5 liters a day, only drinking when I’m thirsty. It’s not a problem.