No problem for two weeks, but be aware that most commercial antifreeze products have corrosion inhibitors in them, so you really don't want to run water long term.
Here's a counter-intuitive tidbit for you. In general, you should use deionized or distilled water in your coolant, along with the antifreeze. However, without the antifreeze, this is probably worse than tap water. Why? Distilled water or deionized water is actually pretty corrosive stuff. The crap in tap water (usually "lime scale" or calcium carbonate) actually makes it less corrosive than ultra-pure water. This is not to say the chlorine in tap water is good for your engine, or that you won't get lime scale if you use tap water long term. That's why coolant flush is usually a mild acid to eat the calcium deposits.
The cheap gallon jugs of water from the grocery store will either be distilled or reverse-osmosis. You want the distilled water.