on the brutes, only the Gray, white, and yellow ones are food grade. You will find only the gray ones @ HD or Lowes. They are fine, and that's what most people use to mix water. If you want to store water, make sure you get the LID to keep stuff out of your water. I have a 55g plastic barrel that I got from one of my LFS, who got it from the local Coke plant. it held syrup for the soda mix, and I am using it as my RODI water storage. I am going to get another one for mixing my SW, or a 44g brute.
here's a pic.