Will they notice that I took some Vodka?

My parents just bought a bottle of vodka. Not the really big bottle but the smaller bottle. Like 750 ml or something instead of the 1.5. I took about 6 oz. Out of it and filled it back up with water. Now it tastes not as strong as vodka usually is. It still burns your throat but doesn't taste the same. 99% of the time they don't take shots, they mix with OJ or Monsters. I'm pretty sure they won't notice, but I guess I need reurance lol.