ok... So... just trying to get a picture of when you are able to consume the liquids you need and give an idea of where you might be able to add something.
Morning shake - 375ml
30 min post shake - start 400ml water - ideally sip and finish by 30 min prior to lunch time.
30 min post lunch - start 400ml water - ideally sip and finish by 30 min prior to dinner time.
30 min post dinner - start 400ml water - OR - the first of two herbal teas - seriously awesome in the winter and flavour without pushing it... 2 teas at 250 ml each would be 500 ml and tea is just something you sip anyway.
That would at least get you to:
375 + 400 + 400 + 400/500 = 1575/1675ml
Now... My own problem with Tea was always that I would wait for it to cool, or forget about it and it got too cold. Thermos makes an AWESOME tea travel cup. It's not cheap but I have 2. I have been known to make a tea, seal it in the cup, leave it on the counter and it is JUST starting to be drinkable as I walk out the door in the morning (8+ hrs later). I made my husband use both of them one time... He bought coffee on the way, took his one tea into the building and nearly burnt his mouth mid morning. Left the other in the car... (Left home at 7 am)... At 2 in the afternoon he went to the car to get the second tea. The outside of it was frosted (stainless steal), but when he went inside and opened it... The tea was still steaming.