2015 Chevy Silverado 2500HD, Improving Unloaded Ride

dasadab wrote:
I was thinking it would be nice to carry the ballast in water and will do so if I can think of a good way to do so without spending too much.

One concern with water is, unless the container is full you'll get sloshing which can add strange movement to the truck. Not to mention leaks. That's why fuel tanks have baffles to limit the slosh. One advantage to sand is you can always use it if you, or someone else stuck on the road, ever needs traction, like on ice or snow.