I don't know how many camping trips I've been on with a cooler full of water by the second day. Bags of ice are not my favorite way to keep the cooler cool! As soon as they melt (which is soon, because the ice is so small), the water leaks all over the cooler and everything gets wet. I got smarter the second time and made sure everything was packaged in waterproof containers, but I was still a wet mess every time I needed to get something out.
On our last trip, I finally figured it out. Freeze gallon jugs of water a few days before you leave. Put the frozen jugs in the cooler with all the food. As the blocks of ice melt, you get cold water to drink, and no water in the cooler.
Our ice (two 1 gallon jugs) kept our food cold for four full days, and filled our water bottles nicely when we were out and about. I will never pack a cooler with a bag of ice again.
Now I just need to get some of those plastic egg containers so I don't end up with broken eggs after cramming the cooler full of food and ice jugs.