A blood test will show a +ve.....regardless of the amount of water youve had.
Whereas if you mean HPT - then yes, it would matter at this stage of your pregnancy (early days) how much water you had drank and what time of day your taking the test.
So your roughly 14 DPO ??? So still early days, not unheard of of faint lines, but still good idea that you went to your doc...

Good Luck.