Excess Drinking Is Bad For You...

Water is a vital source of hydration. It’s the stuff that preserves life, and gives you energy. Considering nearly two thirds of your body consists of water, it makes sense for you to keep your levels topped up throughout the day. It keeps your mind working at its best and prevents loss of concentration, headaches, lack of energy, puffy looking skin, tiredness and irritability.
Water keeps you cool, lubricates your joints and flushes toxins from your body. It's also the fuel that drives your metabolism. So, if you're not drinking enough, you won't burn as many calories as you can - simple as that.
For those of you drinking a lot of tap water, you may need salt.
'Salt!?'
Yes, salt. Let me explain. Without an adequate intake of salt in your water you could very well find yourself dehydrated, even though you are drinking plenty of water. You see your body has a specific salt balance. You are made up of millions of individual cells and the water you drink is stored in these cells, with a set dilution of salt. This salt helps your cells retain the water ingested.
If you drink a lot of water, but you don't have adequate salt in it, the body shuttles the water AND salt out of the cells, into the space surrounding them. From here it is excreted from the body. Over time your body will be excreting more and more water, ever diluting the level of salt in the cells and reducing the level of water retained by these cells. This is when the body becomes dehydrated.
From this perspective water can be considered a diuretic and helps explain why people drinking large amounts of water have to run to the toilet every half an hour. You can actually find yourself in a dehydrated state even though you are drinking an adequate amount of water!
'So, what's the answer?'
Adding a pinch of salt (1/4 teaspoon) to every litre of water you drink throughout the day will make a difference. By salt I mean a high-quality unprocessed sea salt, available from most supermarkets.
If you drink tap water then this is a must. If you have the means to drink 2-3 litres of bottled mineral water each day then there is no need to add salt to your intake. Unless you use a filter for your tap water, you should try and add the required level of salt whenever possible.
Using an empty mineral water bottle makes a good unit of measure, to ensure you are a) sticking to your daily water intake and b) that you are taking in just enough salt. Tap water is just as effective as mineral water in replenishing the body with needed fluid - it just needs a little salt and some purification.
The first thing you will notice once you begin adding salt to your water, aside from the water tasting better, is that you don't need to go to the toilet nearly as often as you had in the past.
After about a week of drinking 2-3 litres a day, your energy levels should become noticeably better and your skin should become much healthier looking. 
So give it a try and see if you don't notice a change in your performance, concentration and general wellbeing.