Our bodies are 60-70% water depending on our size and body type. According to the Journal of Biological Chemistry 158 (H. H. Mitchell), our brains are about 73% water, the same as our hearts.
Studies have shown that as little as 1% dehydration can have an impact on our mood, attention and memory. By the time we feel thirsty we have lost 1-2% of our body's water, so we may already be feeling negative impacts in our mood and cognition before we reach for the glass of water. It may sound silly but being dehydrated can leave you feeling apathetic, anxious, depressed, irritable etc. Pouring and drinking a glass of water is a low effort, zero cost way to (possibly) help yourself feel better. If it doesn't work you have lost nothing.
In this tech age there is an app for everything and for goal oriented people it can be nice to track your progress towards that target. I have been using a hydration app for some time. It allows me to work out what my water consumption goal should be, depending on my body weight, activity levels etc. and tells me how much water each type of drink I consume is contributing to my hydration. All non-alcoholic drinks, even caffeinated ones contribute something.
Alcoholic drinks are truly dehydrating. The app allows me to see how much water I need to consume depending on how much alcohol I'm drinking on that particular day e.g. for every 100ml of wine I drink, I need to drink 160ml of water just to replace the fluids I have lost by consuming the wine. Beer is less dehydrating ml for ml, spirits more so.
Importantly, tracking your water consumption can also allow you to see if you are consuming too much water. You can have too much of a good thing and drinking too much water can interfere with your body's electrolyte balance and leave you feeling quite ill. It can also be pretty dangerous to have an electrolyte imbalance for any length of time so please take extra care if you plan to increase your daily fluid intake.
If you are interested in using an app, have a look in your app store and see what's available. There are a huge variety of trackers. I find the 'My Water' app in the iTunes app store suits my needs just fine.