I had a some credit for the Apple Store so I got an app called Waterllama to remind me to hydrate. Wasn't sure if I was really going to use it but after a week of using it I am glad I got it. Before I was sure I was drinking enough water all day. Getting pinged from the app at regular intervals made me realize I before I was probably drinking a bunch of water mostly in the morning and evening.

You get to set up what you normally drink and then it has a hydration percentage that gets added and subtracted from your daily score. Water is 100% hydration, coffee is 60%, and alcohol is -50%.

Nice to get "am I drinking enough water" out of my head and into an automated system.