Rusty,
Consider the North 49 enviro sac as a general purpose water carrier for a small kit. It is a very tough plastic and has a secure "pop bottle" style lid. It holds 1L of water and is ideal for using water purification tablets, as you can shake or even drop the bag without harm. It can be quickly repaired with duct tape(if you ever manage to puncture it), and cost me a whole 2 dollars. It even comes with a mesh carrier. It is a bit on the bulky side, but very durable. (May make it a worthwhile tradeoff over size) A good old freezer grade Ziploc bag is very hard to beat as well. They are easy to repair and can be rolled very small to fit almost anywhere if size and weight are a concern. I will never try to argue against anyone's opinion on this forum, as everyone has most likely had different experiences than mine. I have tried using a condom to transport water once and it was a pure nightmare. It was nearly impossible to hold and fill in all but the deepest pool of water, more impossible to walk anywhere with, and the slightest prick was enough to break it open and send me back trying to find another means of collecting water. Thank God it was only a training exercise. Just food for thought.