So I've started drinking 2l water a day ....

[Wenchelda]

How long before I notice any difference/improvements? I'm hoping it will brighten my skin, help me feel less sluggish and also aid weight loss (though no chance of that atm with all the Xmas Chocolate still around!) I'm guessing 5 days in is too early to notice a difference?!

I would say a couple of weeks. I did it until the autumn, then returned to work and got out of the habit, which I need to sort out again - I'm drinking too much tea now instead! I felt a lot better for increasing my water intake, except it makes you go to the toilet lots!

keep at it as it does work, and soon you will wonder how did you manage without it.
Also to stop you going to the toilet lots, add tiny bit of salt ( best Himalayan salt) it will help your body to absorb it better.

Add salt to the water, do you mean? Doesn't that make it awful to drink?