A hands free drinking system is a must. Water bottles are not advised.
If you are in a relay, most people use the CamelBak or similar type of water bladder which is contained in a small back pack and has a tube with a one way valve and mouthpiece which comes to the front. The advantages of this system is that you can jump in to the boat very quickly if you are doing rapid changeovers and it stays with you if you capsize. The disadvantages are that they can chafe and rub and also that you are carrying extra weight on your back.
The system nearly all the full distance paddlers use is a 3 litre bladder with a tube and adjustable mouthpiece which incorporates a one way valve. They can be bought at outdoor stores. The secret is to use a common wire coat hanger and some electrical tape and in a couple of minutes you can make a customised harness to wear around your neck. I think the photograph is self explanatory.
[ECK - see our Youtube video of how to make this drinking tube holder]
You can either keep the bladder on the floor of the boat or attach it to the deck elastics if you are in a sea kayak. On a hot day you will need at least 4 litres so either get your land crew to top up the water bladder during the day, or if you are bypassing check points carry a least an extra litre of water.
What to drink?—-Almost every experienced full distance paddler drinks plain water. Drink small amounts and often. If you try and drink sports drinks throughout the day you can encounter problems. However some people report that 200–300ml of sports drink at the middle of the day, followed by a small amount after you finish can be beneficial, but water should still be your main fluid replacement.