I think you just need to listen to your body's needs. I only drank a little over a litre today and my urine was quite clear but I know I needed to drink more as it was 38c today.
I remember when I was BF I was always thirsty and feeling parched so I know the feeling well. 4 litres is 2 bottles of coke and I know a lot of people who would easily drink that in a day so which is more healthier???