I have an idea.. Why not put the water bottles in a plastic tote box with some bubble wrap and place the toter in a duffle bag. Then on your return home use the bubble wrap to wrap your suveniors and place the inside the toter to prevent damage.
Or if you want here is what I have done. I take a bag,(duffle) with me and hop on the DTD bus. When the bus stops at the 2nd DTD bus stop get off. Walk across the street to the Hess gas station and buy a case of water there. Put it in the duffle bag. Walk
back across the street get on the bus going to your resort. The walk to the Hess station takes 5 minutes.
Hubby and I go to Hess to get the water and to grab a slice of pizza and a soda. Go outside sit on the curb enjoy our very cheap meal then go back inside to pick up soda and water to take back to our resort. Hess sells hot fresh pizza, hot dogs, nacho's, fruit, cappachino, laundry soap, water, soda, donuts, coffee cakes, ect. And it is so easy to get to!!!