I know normally feel too thirsty regardless i've just drunk water or not. i often resolve to drink litres and litres of water to no help. please help!?

Excessive thirst: This condition could be related to the following: 1) diabetes; check your sugar. 2) inappropriate ADH (vasopressin) ("kidney diabetes" with excessive loss of water through kidneys; requires blood and urine tests; 3) chronic dehydration, for example, in someone taking diuretics; 4) excess alcohol intake (also causes a problem with adh; 5) a compulsive habit due to anxiety.

You need a doctor: There are medical conditions that can do this, including diabetes mellitus and diabetes insipidus, where the body isn't making hormones that you need, and it results in severe thirst and large volumes of urine. It also can be a psychiatric condition. You need to see a doctor immediately. Water intoxication can cause seizures and brain damage if severe.