It's good to carry water in the car. But maybe you can carry less water and add means of purifying groundwater to meet the same goal? That's what I do. Unless I'm going camping or off into the dessert, I usually only keep 1.5 gallons or so of water in .5L disposable bottles in a latching cooler strapped in the rear of the Jeep. Then I have an MSR Miniworks filter tucked into a saddle bag mounted over the rear fender.

Adding new tie-down points isn't hard to do. Just be sure to use appropriately-sized hardware with fender washers underneath so they don't snap or pull through. Find a good spot, look underneath for obstacles, then drill the holes. Spray the holes both sides with Rustoleum to prevent rust, and secure using fender washers and nylock nuts.

Another solution many off-roaders use is Rotopax containers from Outdoor Products (http://bit.ly/xisY3l). They have a unique mounting system that goes through the center of the container and has proven quite strong, even during rollovers. But the mount doesn't take up a huge amount of room when the container isn't needed.



They are a bit on the spendy side but do make for a safe and neat storage system. Aside from water and fuel containers, they also have storage modules you can fill with tools, food, first aid kits and other gear.

Oh, and as a bonus, they sell non-CARB/ECO replacement spouts that appear to fit standard containers.