We get most of our water from our food, eight glasses a day is a myth.
If you drink too much water you will disturb the electrolyte balance in the body, which can cause heartbeat irregularities.
The quantity of fluid that you excrete as urine should be approximately the same as you take in from all sources (some is lost through sweating and respiration).
Healthy urine is pale yellow and odourless; the urine in the morning will be darker as it is more concentrated because you don't drink at night and the body produces a hormone (AntiDiuretic Hormone) that reduces the quantity of urine produced whilst asleep (at night, it isn't produced so easily if you sleep during the day).
If urine smells fishy or there is pain, burning or stinging on urination then a UTI should be suspected.