Water Leftovers

So I routinely get a cup of water to have at my desk to drink from. But i'm really bad at remembering to drink enough water each day. And usually i am so swamped that all my work days just seem to blur into one long horrendous mega day.

So the bad part is... sometimes i fill up my cup and forget i didn't drink it... so it sits all through the night and the next day... it's still a full cup of water... but is it new? or old? Sometimes I just can't tell. Did i walk over to the dispenser to fill that up this morning... or was i remembering yesterday morning?

I hear you can get sick from drinking 'old' water. But is a day considered old? :) Good thing i have a nice plant for all my water 'leftovers'.