I don't know of any way to protect from loading bad diesel unless you have your own storage tank with good filters on it. However, your main protection is your primary fuel filter. It should have a clear bowl on the bottom of it you can look at daily when driving. In the clear bowl you can see water or contaminates filtering out if they're in your fuel tank. When more than a minor amount appears, drain it out and watch it a little closer for a while.
If your primary doesn't have a clear bowl on it, find a filter that does and change it out. On my Cat C7, I use either Cat or Freightliner/Alliance filters. I'll assume the same is available from Cummins. The filter and the clear bowl are sold separately as the clear bowl doesn't need to be changed very often. I do carry a spare bowl also as they become clouded over time and it's always possible to crack or break one.
You should have at least two sets of spare filters with you in case of contaminated fuel. And I'd tell you to have a third primary filter with you for standard maintenance when you have an oil change. Often the place changing the oil and filters won't have the correct filter on hand using a bowl because it's a little more expensive. When I stopped at Speedco for an oil change recently they didn't have a primary fuel filter to use a bowl with. I had to give them one of mine.
Bill